Re: [PATCH v3 1/2] drm/panthor: Add 64-bit and poll register accessors

From: Liviu Dudau
Date: Tue Apr 15 2025 - 07:32:13 EST

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In reply to: Steven Price: "Re: [PATCH v3 1/2] drm/panthor: Add 64-bit and poll register accessors"
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On Mon, Apr 14, 2025 at 11:41:19AM +0100, Steven Price wrote:
> Hi Karunika,
>
> Minor process thing: There's generally no need to resend a series just
> to add R-b tags - they'll get picked up when the series is merged.
>
> On 11/04/2025 17:48, Karunika Choo wrote:
> > This patch adds 64-bit register accessors to simplify register access in
> > Panthor. It also adds 32-bit and 64-bit variants for read_poll_timeout.
> >
> > This patch also updates Panthor to use the new 64-bit accessors and poll
> > functions.
> >
> > Reviewed-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
> > Signed-off-by: Karunika Choo <karunika.choo@xxxxxxx>

With the changes that Steven suggested:

Reviewed-by: Liviu Dudau <liviu.dudau@xxxxxxx>

Best regards,
Liviu

> > ---
> > drivers/gpu/drm/panthor/panthor_device.h | 71 ++++++++++++
> > drivers/gpu/drm/panthor/panthor_fw.c | 9 +-
> > drivers/gpu/drm/panthor/panthor_gpu.c | 142 ++++++-----------------
> > drivers/gpu/drm/panthor/panthor_mmu.c | 34 ++----
> > drivers/gpu/drm/panthor/panthor_regs.h | 6 -
> > 5 files changed, 124 insertions(+), 138 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/panthor/panthor_device.h b/drivers/gpu/drm/panthor/panthor_device.h
> > index da6574021664..40b935fcc1f4 100644
> > --- a/drivers/gpu/drm/panthor/panthor_device.h
> > +++ b/drivers/gpu/drm/panthor/panthor_device.h
> > @@ -428,4 +428,75 @@ static int panthor_request_ ## __name ## _irq(struct panthor_device *ptdev, \
> >
> > extern struct workqueue_struct *panthor_cleanup_wq;
> >
> > +static inline void gpu_write(struct panthor_device *ptdev, u32 reg, u32 data)
> > +{
> > + writel(data, ptdev->iomem + reg);
> > +}
> > +
> > +static inline u32 gpu_read(struct panthor_device *ptdev, u32 reg)
> > +{
> > + return readl(ptdev->iomem + reg);
> > +}
> > +
> > +static inline u32 gpu_read_relaxed(struct panthor_device *ptdev, u32 reg)
> > +{
> > + return readl_relaxed(ptdev->iomem + reg);
> > +}
> > +
> > +static inline void gpu_write64(struct panthor_device *ptdev, u32 reg, u64 data)
> > +{
> > + gpu_write(ptdev, reg, lower_32_bits(data));
> > + gpu_write(ptdev, reg + 4, upper_32_bits(data));
> > +}
> > +
> > +static inline u64 gpu_read64(struct panthor_device *ptdev, u32 reg)
> > +{
> > + return (gpu_read(ptdev, reg) | ((u64)gpu_read(ptdev, reg + 4) << 32));
> > +}
> > +
> > +static inline u64 gpu_read64_relaxed(struct panthor_device *ptdev, u32 reg)
> > +{
> > + return (gpu_read_relaxed(ptdev, reg) |
> > + ((u64)gpu_read_relaxed(ptdev, reg + 4) << 32));
> > +}
> > +
> > +static inline u64 gpu_read64_counter(struct panthor_device *ptdev, u32 reg)
> > +{
> > + u32 lo, hi1, hi2;
> > + do {
> > + hi1 = gpu_read(ptdev, reg + 4);
> > + lo = gpu_read(ptdev, reg);
> > + hi2 = gpu_read(ptdev, reg + 4);
> > + } while (hi1 != hi2);
> > + return lo | ((u64)hi2 << 32);
> > +}
> > +
> > +#define gpu_read_poll_timeout(dev, reg, val, cond, delay_us, timeout_us) \
> > + read_poll_timeout(gpu_read, val, cond, delay_us, timeout_us, false, \
> > + dev, reg)
> > +
> > +#define gpu_read_poll_timeout_atomic(dev, reg, val, cond, delay_us, \
> > + timeout_us) \
> > + read_poll_timeout_atomic(gpu_read, val, cond, delay_us, timeout_us, \
> > + false, dev, reg)
> > +
> > +#define gpu_read64_poll_timeout(dev, reg, val, cond, delay_us, timeout_us) \
> > + read_poll_timeout(gpu_read64, val, cond, delay_us, timeout_us, false, \
> > + dev, reg)
> > +
> > +#define gpu_read64_poll_timeout_atomic(dev, reg, val, cond, delay_us, \
> > + timeout_us) \
> > + read_poll_timeout_atomic(gpu_read64, val, cond, delay_us, timeout_us, \
> > + false, dev, reg)
> > +
> > +#define gpu_read_relaxed_poll_timeout_atomic(dev, reg, val, cond, delay_us, \
> > + timeout_us) \
> > + read_poll_timeout_atomic(gpu_read_relaxed, val, cond, delay_us, \
> > + timeout_us, false, dev, reg)
> > +
> > +#define gpu_read64_relaxed_poll_timeout(dev, reg, val, cond, delay_us, \
> > + timeout_us) \
> > + read_poll_timeout(gpu_read64_relaxed, val, cond, delay_us, timeout_us, \
> > + false, dev, reg)
> > +
> > #endif
> > diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
> > index 0f52766a3120..ecfbe0456f89 100644
> > --- a/drivers/gpu/drm/panthor/panthor_fw.c
> > +++ b/drivers/gpu/drm/panthor/panthor_fw.c
> > @@ -1059,8 +1059,8 @@ static void panthor_fw_stop(struct panthor_device *ptdev)
> > u32 status;
> >
> > gpu_write(ptdev, MCU_CONTROL, MCU_CONTROL_DISABLE);
> > - if (readl_poll_timeout(ptdev->iomem + MCU_STATUS, status,
> > - status == MCU_STATUS_DISABLED, 10, 100000))
> > + if (gpu_read_poll_timeout(ptdev, MCU_STATUS, status,
> > + status == MCU_STATUS_DISABLED, 10, 100000))
> > drm_err(&ptdev->base, "Failed to stop MCU");
> > }
> >
> > @@ -1085,8 +1085,9 @@ void panthor_fw_pre_reset(struct panthor_device *ptdev, bool on_hang)
> >
> > panthor_fw_update_reqs(glb_iface, req, GLB_HALT, GLB_HALT);
> > gpu_write(ptdev, CSF_DOORBELL(CSF_GLB_DOORBELL_ID), 1);
> > - if (!readl_poll_timeout(ptdev->iomem + MCU_STATUS, status,
> > - status == MCU_STATUS_HALT, 10, 100000)) {
> > + if (!gpu_read_poll_timeout(ptdev, MCU_STATUS, status,
> > + status == MCU_STATUS_HALT, 10,
> > + 100000)) {
> > ptdev->reset.fast = true;
> > } else {
> > drm_warn(&ptdev->base, "Failed to cleanly suspend MCU");
> > diff --git a/drivers/gpu/drm/panthor/panthor_gpu.c b/drivers/gpu/drm/panthor/panthor_gpu.c
> > index 671049020afa..fd09f0928019 100644
> > --- a/drivers/gpu/drm/panthor/panthor_gpu.c
> > +++ b/drivers/gpu/drm/panthor/panthor_gpu.c
> > @@ -108,14 +108,9 @@ static void panthor_gpu_init_info(struct panthor_device *ptdev)
> >
> > ptdev->gpu_info.as_present = gpu_read(ptdev, GPU_AS_PRESENT);
> >
> > - ptdev->gpu_info.shader_present = gpu_read(ptdev, GPU_SHADER_PRESENT_LO);
> > - ptdev->gpu_info.shader_present |= (u64)gpu_read(ptdev, GPU_SHADER_PRESENT_HI) << 32;
> > -
> > - ptdev->gpu_info.tiler_present = gpu_read(ptdev, GPU_TILER_PRESENT_LO);
> > - ptdev->gpu_info.tiler_present |= (u64)gpu_read(ptdev, GPU_TILER_PRESENT_HI) << 32;
> > -
> > - ptdev->gpu_info.l2_present = gpu_read(ptdev, GPU_L2_PRESENT_LO);
> > - ptdev->gpu_info.l2_present |= (u64)gpu_read(ptdev, GPU_L2_PRESENT_HI) << 32;
> > + ptdev->gpu_info.shader_present = gpu_read64(ptdev, GPU_SHADER_PRESENT_LO);
> > + ptdev->gpu_info.tiler_present = gpu_read64(ptdev, GPU_TILER_PRESENT_LO);
> > + ptdev->gpu_info.l2_present = gpu_read64(ptdev, GPU_L2_PRESENT_LO);
> >
> > arch_major = GPU_ARCH_MAJOR(ptdev->gpu_info.gpu_id);
> > product_major = GPU_PROD_MAJOR(ptdev->gpu_info.gpu_id);
> > @@ -152,8 +147,7 @@ static void panthor_gpu_irq_handler(struct panthor_device *ptdev, u32 status)
> > {
> > if (status & GPU_IRQ_FAULT) {
> > u32 fault_status = gpu_read(ptdev, GPU_FAULT_STATUS);
> > - u64 address = ((u64)gpu_read(ptdev, GPU_FAULT_ADDR_HI) << 32) |
> > - gpu_read(ptdev, GPU_FAULT_ADDR_LO);
> > + u64 address = gpu_read64(ptdev, GPU_FAULT_ADDR_LO);
> >
> > drm_warn(&ptdev->base, "GPU Fault 0x%08x (%s) at 0x%016llx\n",
> > fault_status, panthor_exception_name(ptdev, fault_status & 0xFF),
> > @@ -244,45 +238,27 @@ int panthor_gpu_block_power_off(struct panthor_device *ptdev,
> > u32 pwroff_reg, u32 pwrtrans_reg,
> > u64 mask, u32 timeout_us)
> > {
> > - u32 val, i;
> > + u32 val;
> > int ret;
> >
> > - for (i = 0; i < 2; i++) {
> > - u32 mask32 = mask >> (i * 32);
> > -
> > - if (!mask32)
> > - continue;
> > -
> > - ret = readl_relaxed_poll_timeout(ptdev->iomem + pwrtrans_reg + (i * 4),
> > - val, !(mask32 & val),
> > - 100, timeout_us);
> > - if (ret) {
> > - drm_err(&ptdev->base, "timeout waiting on %s:%llx power transition",
> > - blk_name, mask);
> > - return ret;
> > - }
> > + ret = gpu_read64_relaxed_poll_timeout(ptdev, pwrtrans_reg, val, !val,
> > + 100, timeout_us);
>
> You're ignoring "mask" here, so there's a change in behaviour. I think
> you want:
>
> ret = gpu_read64_relaxed_poll_timeout(ptdev, pwrtrans_reg, val,
> !(mask & val),
> 100, timeout_us);
>
> (although I doubt it makes much difference in reality)
>
> > + if (ret) {
> > + drm_err(&ptdev->base,
> > + "timeout waiting on %s:%llx power transition", blk_name,
> > + mask);
> > + return ret;
> > }
> >
> > - if (mask & GENMASK(31, 0))
> > - gpu_write(ptdev, pwroff_reg, mask);
> > -
> > - if (mask >> 32)
> > - gpu_write(ptdev, pwroff_reg + 4, mask >> 32);
> > -
> > - for (i = 0; i < 2; i++) {
> > - u32 mask32 = mask >> (i * 32);
> > + gpu_write64(ptdev, pwroff_reg, mask);
> >
> > - if (!mask32)
> > - continue;
> > -
> > - ret = readl_relaxed_poll_timeout(ptdev->iomem + pwrtrans_reg + (i * 4),
> > - val, !(mask32 & val),
> > - 100, timeout_us);
> > - if (ret) {
> > - drm_err(&ptdev->base, "timeout waiting on %s:%llx power transition",
> > - blk_name, mask);
> > - return ret;
> > - }
> > + ret = gpu_read64_relaxed_poll_timeout(ptdev, pwrtrans_reg, val, !val,
> > + 100, timeout_us);
>
> Same here and two more below.
>
> > + if (ret) {
> > + drm_err(&ptdev->base,
> > + "timeout waiting on %s:%llx power transition", blk_name,
> > + mask);
> > + return ret;
> > }
> >
> > return 0;
> > @@ -305,45 +281,26 @@ int panthor_gpu_block_power_on(struct panthor_device *ptdev,
> > u32 pwron_reg, u32 pwrtrans_reg,
> > u32 rdy_reg, u64 mask, u32 timeout_us)
> > {
> > - u32 val, i;
> > + u32 val;
> > int ret;
> >
> > - for (i = 0; i < 2; i++) {
> > - u32 mask32 = mask >> (i * 32);
> > -
> > - if (!mask32)
> > - continue;
> > -
> > - ret = readl_relaxed_poll_timeout(ptdev->iomem + pwrtrans_reg + (i * 4),
> > - val, !(mask32 & val),
> > - 100, timeout_us);
> > - if (ret) {
> > - drm_err(&ptdev->base, "timeout waiting on %s:%llx power transition",
> > - blk_name, mask);
> > - return ret;
> > - }
> > + ret = gpu_read64_relaxed_poll_timeout(ptdev, pwrtrans_reg, val, !val,
> > + 100, timeout_us);
> > + if (ret) {
> > + drm_err(&ptdev->base,
> > + "timeout waiting on %s:%llx power transition", blk_name,
> > + mask);
> > + return ret;
> > }
> >
> > - if (mask & GENMASK(31, 0))
> > - gpu_write(ptdev, pwron_reg, mask);
> > -
> > - if (mask >> 32)
> > - gpu_write(ptdev, pwron_reg + 4, mask >> 32);
> > -
> > - for (i = 0; i < 2; i++) {
> > - u32 mask32 = mask >> (i * 32);
> > + gpu_write64(ptdev, pwron_reg, mask);
> >
> > - if (!mask32)
> > - continue;
> > -
> > - ret = readl_relaxed_poll_timeout(ptdev->iomem + rdy_reg + (i * 4),
> > - val, (mask32 & val) == mask32,
> > - 100, timeout_us);
> > - if (ret) {
> > - drm_err(&ptdev->base, "timeout waiting on %s:%llx readiness",
> > - blk_name, mask);
> > - return ret;
> > - }
> > + ret = gpu_read64_relaxed_poll_timeout(ptdev, pwrtrans_reg, val, !val,
> > + 100, timeout_us);
> > + if (ret) {
> > + drm_err(&ptdev->base, "timeout waiting on %s:%llx readiness",
> > + blk_name, mask);
> > + return ret;
> > }
> >
> > return 0;
> > @@ -492,26 +449,6 @@ void panthor_gpu_resume(struct panthor_device *ptdev)
> > panthor_gpu_l2_power_on(ptdev);
> > }
> >
> > -/**
> > - * panthor_gpu_read_64bit_counter() - Read a 64-bit counter at a given offset.
> > - * @ptdev: Device.
> > - * @reg: The offset of the register to read.
> > - *
> > - * Return: The counter value.
> > - */
> > -static u64
> > -panthor_gpu_read_64bit_counter(struct panthor_device *ptdev, u32 reg)
> > -{
> > - u32 hi, lo;
> > -
> > - do {
> > - hi = gpu_read(ptdev, reg + 0x4);
> > - lo = gpu_read(ptdev, reg);
> > - } while (hi != gpu_read(ptdev, reg + 0x4));
> > -
> > - return ((u64)hi << 32) | lo;
> > -}
> > -
> > /**
> > * panthor_gpu_read_timestamp() - Read the timestamp register.
> > * @ptdev: Device.
> > @@ -520,7 +457,7 @@ panthor_gpu_read_64bit_counter(struct panthor_device *ptdev, u32 reg)
> > */
> > u64 panthor_gpu_read_timestamp(struct panthor_device *ptdev)
> > {
> > - return panthor_gpu_read_64bit_counter(ptdev, GPU_TIMESTAMP_LO);
> > + return gpu_read64_counter(ptdev, GPU_TIMESTAMP_LO);
> > }
> >
> > /**
> > @@ -531,10 +468,5 @@ u64 panthor_gpu_read_timestamp(struct panthor_device *ptdev)
> > */
> > u64 panthor_gpu_read_timestamp_offset(struct panthor_device *ptdev)
> > {
> > - u32 hi, lo;
> > -
> > - hi = gpu_read(ptdev, GPU_TIMESTAMP_OFFSET_HI);
> > - lo = gpu_read(ptdev, GPU_TIMESTAMP_OFFSET_LO);
> > -
> > - return ((u64)hi << 32) | lo;
> > + return gpu_read64(ptdev, GPU_TIMESTAMP_OFFSET_LO);
> > }
>
> We might as well drop this function and inline the gpu_read64() call.
>
> Thanks,
> Steve
>
> > diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
> > index 12a02e28f50f..a0a79f19bdea 100644
> > --- a/drivers/gpu/drm/panthor/panthor_mmu.c
> > +++ b/drivers/gpu/drm/panthor/panthor_mmu.c
> > @@ -510,9 +510,9 @@ static int wait_ready(struct panthor_device *ptdev, u32 as_nr)
> > /* Wait for the MMU status to indicate there is no active command, in
> > * case one is pending.
> > */
> > - ret = readl_relaxed_poll_timeout_atomic(ptdev->iomem + AS_STATUS(as_nr),
> > - val, !(val & AS_STATUS_AS_ACTIVE),
> > - 10, 100000);
> > + ret = gpu_read_relaxed_poll_timeout_atomic(ptdev, AS_STATUS(as_nr), val,
> > + !(val & AS_STATUS_AS_ACTIVE),
> > + 10, 100000);
> >
> > if (ret) {
> > panthor_device_schedule_reset(ptdev);
> > @@ -564,8 +564,7 @@ static void lock_region(struct panthor_device *ptdev, u32 as_nr,
> > region = region_width | region_start;
> >
> > /* Lock the region that needs to be updated */
> > - gpu_write(ptdev, AS_LOCKADDR_LO(as_nr), lower_32_bits(region));
> > - gpu_write(ptdev, AS_LOCKADDR_HI(as_nr), upper_32_bits(region));
> > + gpu_write64(ptdev, AS_LOCKADDR_LO(as_nr), region);
> > write_cmd(ptdev, as_nr, AS_COMMAND_LOCK);
> > }
> >
> > @@ -615,14 +614,9 @@ static int panthor_mmu_as_enable(struct panthor_device *ptdev, u32 as_nr,
> > if (ret)
> > return ret;
> >
> > - gpu_write(ptdev, AS_TRANSTAB_LO(as_nr), lower_32_bits(transtab));
> > - gpu_write(ptdev, AS_TRANSTAB_HI(as_nr), upper_32_bits(transtab));
> > -
> > - gpu_write(ptdev, AS_MEMATTR_LO(as_nr), lower_32_bits(memattr));
> > - gpu_write(ptdev, AS_MEMATTR_HI(as_nr), upper_32_bits(memattr));
> > -
> > - gpu_write(ptdev, AS_TRANSCFG_LO(as_nr), lower_32_bits(transcfg));
> > - gpu_write(ptdev, AS_TRANSCFG_HI(as_nr), upper_32_bits(transcfg));
> > + gpu_write64(ptdev, AS_TRANSTAB_LO(as_nr), transtab);
> > + gpu_write64(ptdev, AS_MEMATTR_LO(as_nr), memattr);
> > + gpu_write64(ptdev, AS_TRANSCFG_LO(as_nr), transcfg);
> >
> > return write_cmd(ptdev, as_nr, AS_COMMAND_UPDATE);
> > }
> > @@ -635,14 +629,9 @@ static int panthor_mmu_as_disable(struct panthor_device *ptdev, u32 as_nr)
> > if (ret)
> > return ret;
> >
> > - gpu_write(ptdev, AS_TRANSTAB_LO(as_nr), 0);
> > - gpu_write(ptdev, AS_TRANSTAB_HI(as_nr), 0);
> > -
> > - gpu_write(ptdev, AS_MEMATTR_LO(as_nr), 0);
> > - gpu_write(ptdev, AS_MEMATTR_HI(as_nr), 0);
> > -
> > - gpu_write(ptdev, AS_TRANSCFG_LO(as_nr), AS_TRANSCFG_ADRMODE_UNMAPPED);
> > - gpu_write(ptdev, AS_TRANSCFG_HI(as_nr), 0);
> > + gpu_write64(ptdev, AS_TRANSTAB_LO(as_nr), 0);
> > + gpu_write64(ptdev, AS_MEMATTR_LO(as_nr), 0);
> > + gpu_write64(ptdev, AS_TRANSCFG_LO(as_nr), AS_TRANSCFG_ADRMODE_UNMAPPED);
> >
> > return write_cmd(ptdev, as_nr, AS_COMMAND_UPDATE);
> > }
> > @@ -1680,8 +1669,7 @@ static void panthor_mmu_irq_handler(struct panthor_device *ptdev, u32 status)
> > u32 source_id;
> >
> > fault_status = gpu_read(ptdev, AS_FAULTSTATUS(as));
> > - addr = gpu_read(ptdev, AS_FAULTADDRESS_LO(as));
> > - addr |= (u64)gpu_read(ptdev, AS_FAULTADDRESS_HI(as)) << 32;
> > + addr = gpu_read64(ptdev, AS_FAULTADDRESS_LO(as));
> >
> > /* decode the fault status */
> > exception_type = fault_status & 0xFF;
> > diff --git a/drivers/gpu/drm/panthor/panthor_regs.h b/drivers/gpu/drm/panthor/panthor_regs.h
> > index a3ced0177535..6fd39a52f887 100644
> > --- a/drivers/gpu/drm/panthor/panthor_regs.h
> > +++ b/drivers/gpu/drm/panthor/panthor_regs.h
> > @@ -232,10 +232,4 @@
> > #define CSF_DOORBELL(i) (0x80000 + ((i) * 0x10000))
> > #define CSF_GLB_DOORBELL_ID 0
> >
> > -#define gpu_write(dev, reg, data) \
> > - writel(data, (dev)->iomem + (reg))
> > -
> > -#define gpu_read(dev, reg) \
> > - readl((dev)->iomem + (reg))
> > -
> > #endif
>

--
====================
| I would like to |
| fix the world, |
| but they're not |
| giving me the |
\ source code! /
---------------
¯\_(ツ)_/¯

Next message: Greg Kroah-Hartman: "Re: [PATCH v2 RESEND] intel_th: avoid using deprecated page->mapping, index fields"
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Next in thread: Karunika Choo: "[PATCH v3 2/2] drm/panthor: Clean up 64-bit register definitions"
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