RE: [EXT] Re: [PATCH v5 01/10] drm: bridge: cadence: convert mailbox functions to macro functions
From: Sandor Yu
Date: Mon Dec 12 2022 - 03:02:49 EST
Hi Lucas,
Thanks your comments,
> -----Original Message-----
> From: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
> Sent: 2022年12月9日 19:30
> To: Sandor Yu <sandor.yu@xxxxxxx>; andrzej.hajda@xxxxxxxxx;
> neil.armstrong@xxxxxxxxxx; robert.foss@xxxxxxxxxx;
> Laurent.pinchart@xxxxxxxxxxxxxxxx; jonas@xxxxxxxxx;
> jernej.skrabec@xxxxxxxxx; airlied@xxxxxxxxx; daniel@xxxxxxxx;
> robh+dt@xxxxxxxxxx; krzysztof.kozlowski+dt@xxxxxxxxxx;
> shawnguo@xxxxxxxxxx; s.hauer@xxxxxxxxxxxxxx; festevam@xxxxxxxxx;
> vkoul@xxxxxxxxxx; dri-devel@xxxxxxxxxxxxxxxxxxxxx;
> devicetree@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx;
> linux-kernel@xxxxxxxxxxxxxxx; linux-phy@xxxxxxxxxxxxxxxxxxx
> Cc: Oliver Brown <oliver.brown@xxxxxxx>; dl-linux-imx
> <linux-imx@xxxxxxx>; kernel@xxxxxxxxxxxxxx
> Subject: [EXT] Re: [PATCH v5 01/10] drm: bridge: cadence: convert mailbox
> functions to macro functions
>
> Caution: EXT Email
>
> Hi Sandor,
>
> Am Montag, dem 28.11.2022 um 15:36 +0800 schrieb Sandor Yu:
> > Mailbox access functions could be share to other mhdp driver and
> > HDP-TX HDMI/DP PHY drivers, move those functions to head file
> > include/drm/bridge/cdns-mhdp-mailbox.h and convert them to macro
> > functions.
> >
>
> This does not look right. If those functions need to be called from other units
> and implemented in the header, they should simply be static inline functions
> rather than macros. Those macros obfuscate the code a lot.
>
> However, I don't believe those should be called by other units directly. From
> what I can see this is mostly used by the PHY drivers, to interact with the
> mailbox and read/write PHY registers. However, there is no locking between
> the bridge and the core driver in any form, so they could corrupt the mailbox
> state. The PHY drivers have mailbox mutexes, but as far as I can see they
> aren't used and even if they were they would not guard against concurrent
> access to the mailbox between the bridge and the PHY driver.
Both PHY and bridge have its owner mutex to lock mailbox read/write.
In bridge driver, this mutex also lock for PHY API function access to avoid PHY and bridge driver race condition.
>
> I think the right thing to do here would be to have a regmap implementation
> in the bridge driver, which uses the mailbox functions to implement the
> register access. Then this regmap could be passed down from the bridge
> driver to the PHY, which should simply be a child node of the bridge in DT.
>
I'm not sure got your point " regmap implementation in the bridge driver".
Those mailbox functions also should be reused by mhdp8546.
Could you please explain detail or provide a sample?
Regards,
Sandor
> Regards,
> Lucas
>
> > Signed-off-by: Sandor Yu <Sandor.yu@xxxxxxx>
> > ---
> > .../drm/bridge/cadence/cdns-mhdp8546-core.c | 197 +-------------
> > .../drm/bridge/cadence/cdns-mhdp8546-core.h | 1 -
> > include/drm/bridge/cdns-mhdp-mailbox.h | 240
> ++++++++++++++++++
> > 3 files changed, 242 insertions(+), 196 deletions(-) create mode
> > 100644 include/drm/bridge/cdns-mhdp-mailbox.h
> >
> > diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> > b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> > index 31442a922502..b77b0ddcc9b3 100644
> > --- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> > +++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> > @@ -36,6 +36,7 @@
> > #include <linux/slab.h>
> > #include <linux/wait.h>
> >
> > +#include <drm/bridge/cdns-mhdp-mailbox.h>
> > #include <drm/display/drm_dp_helper.h> #include
> > <drm/display/drm_hdcp_helper.h> #include <drm/drm_atomic.h> @@
> > -55,200 +56,6 @@ #include "cdns-mhdp8546-hdcp.h"
> > #include "cdns-mhdp8546-j721e.h"
> >
> > -static int cdns_mhdp_mailbox_read(struct cdns_mhdp_device *mhdp) -{
> > - int ret, empty;
> > -
> > - WARN_ON(!mutex_is_locked(&mhdp->mbox_mutex));
> > -
> > - ret = readx_poll_timeout(readl, mhdp->regs +
> CDNS_MAILBOX_EMPTY,
> > - empty, !empty, MAILBOX_RETRY_US,
> > - MAILBOX_TIMEOUT_US);
> > - if (ret < 0)
> > - return ret;
> > -
> > - return readl(mhdp->regs + CDNS_MAILBOX_RX_DATA) & 0xff;
> > -}
> > -
> > -static int cdns_mhdp_mailbox_write(struct cdns_mhdp_device *mhdp, u8
> > val) -{
> > - int ret, full;
> > -
> > - WARN_ON(!mutex_is_locked(&mhdp->mbox_mutex));
> > -
> > - ret = readx_poll_timeout(readl, mhdp->regs +
> CDNS_MAILBOX_FULL,
> > - full, !full, MAILBOX_RETRY_US,
> > - MAILBOX_TIMEOUT_US);
> > - if (ret < 0)
> > - return ret;
> > -
> > - writel(val, mhdp->regs + CDNS_MAILBOX_TX_DATA);
> > -
> > - return 0;
> > -}
> > -
> > -static int cdns_mhdp_mailbox_recv_header(struct cdns_mhdp_device
> *mhdp,
> > - u8 module_id, u8 opcode,
> > - u16 req_size)
> > -{
> > - u32 mbox_size, i;
> > - u8 header[4];
> > - int ret;
> > -
> > - /* read the header of the message */
> > - for (i = 0; i < sizeof(header); i++) {
> > - ret = cdns_mhdp_mailbox_read(mhdp);
> > - if (ret < 0)
> > - return ret;
> > -
> > - header[i] = ret;
> > - }
> > -
> > - mbox_size = get_unaligned_be16(header + 2);
> > -
> > - if (opcode != header[0] || module_id != header[1] ||
> > - req_size != mbox_size) {
> > - /*
> > - * If the message in mailbox is not what we want, we need
> to
> > - * clear the mailbox by reading its contents.
> > - */
> > - for (i = 0; i < mbox_size; i++)
> > - if (cdns_mhdp_mailbox_read(mhdp) < 0)
> > - break;
> > -
> > - return -EINVAL;
> > - }
> > -
> > - return 0;
> > -}
> > -
> > -static int cdns_mhdp_mailbox_recv_data(struct cdns_mhdp_device
> *mhdp,
> > - u8 *buff, u16 buff_size)
> > -{
> > - u32 i;
> > - int ret;
> > -
> > - for (i = 0; i < buff_size; i++) {
> > - ret = cdns_mhdp_mailbox_read(mhdp);
> > - if (ret < 0)
> > - return ret;
> > -
> > - buff[i] = ret;
> > - }
> > -
> > - return 0;
> > -}
> > -
> > -static int cdns_mhdp_mailbox_send(struct cdns_mhdp_device *mhdp, u8
> module_id,
> > - u8 opcode, u16 size, u8 *message)
> > -{
> > - u8 header[4];
> > - int ret, i;
> > -
> > - header[0] = opcode;
> > - header[1] = module_id;
> > - put_unaligned_be16(size, header + 2);
> > -
> > - for (i = 0; i < sizeof(header); i++) {
> > - ret = cdns_mhdp_mailbox_write(mhdp, header[i]);
> > - if (ret)
> > - return ret;
> > - }
> > -
> > - for (i = 0; i < size; i++) {
> > - ret = cdns_mhdp_mailbox_write(mhdp, message[i]);
> > - if (ret)
> > - return ret;
> > - }
> > -
> > - return 0;
> > -}
> > -
> > -static
> > -int cdns_mhdp_reg_read(struct cdns_mhdp_device *mhdp, u32 addr, u32
> > *value) -{
> > - u8 msg[4], resp[8];
> > - int ret;
> > -
> > - put_unaligned_be32(addr, msg);
> > -
> > - mutex_lock(&mhdp->mbox_mutex);
> > -
> > - ret = cdns_mhdp_mailbox_send(mhdp, MB_MODULE_ID_GENERAL,
> > - GENERAL_REGISTER_READ,
> > - sizeof(msg), msg);
> > - if (ret)
> > - goto out;
> > -
> > - ret = cdns_mhdp_mailbox_recv_header(mhdp,
> MB_MODULE_ID_GENERAL,
> > -
> GENERAL_REGISTER_READ,
> > - sizeof(resp));
> > - if (ret)
> > - goto out;
> > -
> > - ret = cdns_mhdp_mailbox_recv_data(mhdp, resp, sizeof(resp));
> > - if (ret)
> > - goto out;
> > -
> > - /* Returned address value should be the same as requested */
> > - if (memcmp(msg, resp, sizeof(msg))) {
> > - ret = -EINVAL;
> > - goto out;
> > - }
> > -
> > - *value = get_unaligned_be32(resp + 4);
> > -
> > -out:
> > - mutex_unlock(&mhdp->mbox_mutex);
> > - if (ret) {
> > - dev_err(mhdp->dev, "Failed to read register\n");
> > - *value = 0;
> > - }
> > -
> > - return ret;
> > -}
> > -
> > -static
> > -int cdns_mhdp_reg_write(struct cdns_mhdp_device *mhdp, u16 addr, u32
> > val) -{
> > - u8 msg[6];
> > - int ret;
> > -
> > - put_unaligned_be16(addr, msg);
> > - put_unaligned_be32(val, msg + 2);
> > -
> > - mutex_lock(&mhdp->mbox_mutex);
> > -
> > - ret = cdns_mhdp_mailbox_send(mhdp, MB_MODULE_ID_DP_TX,
> > - DPTX_WRITE_REGISTER,
> sizeof(msg), msg);
> > -
> > - mutex_unlock(&mhdp->mbox_mutex);
> > -
> > - return ret;
> > -}
> > -
> > -static
> > -int cdns_mhdp_reg_write_bit(struct cdns_mhdp_device *mhdp, u16 addr,
> > - u8 start_bit, u8 bits_no, u32 val)
> > -{
> > - u8 field[8];
> > - int ret;
> > -
> > - put_unaligned_be16(addr, field);
> > - field[2] = start_bit;
> > - field[3] = bits_no;
> > - put_unaligned_be32(val, field + 4);
> > -
> > - mutex_lock(&mhdp->mbox_mutex);
> > -
> > - ret = cdns_mhdp_mailbox_send(mhdp, MB_MODULE_ID_DP_TX,
> > - DPTX_WRITE_FIELD, sizeof(field),
> field);
> > -
> > - mutex_unlock(&mhdp->mbox_mutex);
> > -
> > - return ret;
> > -}
> > -
> > static
> > int cdns_mhdp_dpcd_read(struct cdns_mhdp_device *mhdp,
> > u32 addr, u8 *data, u16 len) @@ -2058,7
> +1865,7
> > @@ static void cdns_mhdp_atomic_disable(struct drm_bridge *bridge,
> > struct drm_bridge_state
> > *bridge_state) {
> > struct cdns_mhdp_device *mhdp = bridge_to_mhdp(bridge);
> > - u32 resp;
> > + u32 resp = 0;
> >
> > dev_dbg(mhdp->dev, "%s\n", __func__);
> >
> > diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h
> > b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h
> > index bedddd510d17..10c878bf0e63 100644
> > --- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h
> > +++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h
> > @@ -212,7 +212,6 @@ struct phy;
> > #define MB_MODULE_ID_HDCP_TX 0x07
> > #define MB_MODULE_ID_HDCP_RX 0x08
> > #define MB_MODULE_ID_HDCP_GENERAL 0x09
> > -#define MB_MODULE_ID_GENERAL 0x0a
> >
> > /* firmware and opcodes */
> > #define FW_NAME
> "cadence/mhdp8546.bin"
> > diff --git a/include/drm/bridge/cdns-mhdp-mailbox.h
> > b/include/drm/bridge/cdns-mhdp-mailbox.h
> > new file mode 100644
> > index 000000000000..0249322a74b0
> > --- /dev/null
> > +++ b/include/drm/bridge/cdns-mhdp-mailbox.h
> > @@ -0,0 +1,240 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +/*
> > + * Cadence MHDP Firmware Access API function by Malibox.
> > + *
> > + * Copyright (C) 2022 NXP Semiconductor, Inc.
> > + *
> > + */
> > +#ifndef CDNS_MHDP_MAILBOX_H
> > +#define CDNS_MHDP_MAILBOX_H
> > +
> > +#include <asm/unaligned.h>
> > +#include <linux/iopoll.h>
> > +
> > +/* mailbox regs offset */
> > +#define CDNS_MAILBOX_FULL 0x00008
> > +#define CDNS_MAILBOX_EMPTY 0x0000c
> > +#define CDNS_MAILBOX_TX_DATA 0x00010
> > +#define CDNS_MAILBOX_RX_DATA 0x00014
> > +
> > +#define MAILBOX_RETRY_US 1000
> > +#define MAILBOX_TIMEOUT_US 2000000
> > +
> > +/* Module ID Code */
> > +#define MB_MODULE_ID_GENERAL 0x0A
> > +#define MB_MODULE_ID_DP_TX 0x01
> > +
> > +/* General Commands */
> > +#define GENERAL_REGISTER_WRITE 0x05
> > +#define GENERAL_REGISTER_READ 0x07
> > +
> > +/* DP TX Command */
> > +#define DPTX_WRITE_FIELD 0x08
> > +
> > +/* MHDP Firmware access functions by Mailbox */ #define
> > +cdns_mhdp_mailbox_read(__mhdp) \ ({ \
> > + int ret, empty, val; \
> > +\
> > + WARN_ON(!mutex_is_locked(&(__mhdp)->mbox_mutex)); \ \
> > + do { \
> > + ret = readx_poll_timeout(readl, (__mhdp)->regs +
> CDNS_MAILBOX_EMPTY, \
> > + empty, !empty,
> MAILBOX_RETRY_US, \
> > + MAILBOX_TIMEOUT_US);
> \
> > + if (ret < 0) \
> > + break; \
> > +\
> > + val = readl((__mhdp)->regs + CDNS_MAILBOX_RX_DATA)
> & 0xff; \
> > + } while (0); \
> > +\
> > + (ret < 0) ? ret : val; \
> > +})
> > +
> > +#define cdns_mhdp_mailbox_write(__mhdp, __val) \ ({ \
> > + int ret, full; \
> > +\
> > + WARN_ON(!mutex_is_locked(&(__mhdp)->mbox_mutex)); \ \
> > + do { \
> > + ret = readx_poll_timeout(readl, (__mhdp)->regs +
> CDNS_MAILBOX_FULL, \
> > + full, !full,
> MAILBOX_RETRY_US, \
> > + MAILBOX_TIMEOUT_US);
> \
> > + if (ret < 0) \
> > + break; \
> > +\
> > + writel((__val), (__mhdp)->regs +
> CDNS_MAILBOX_TX_DATA); \
> > + } while (0); \
> > +\
> > + ret; \
> > +})
> > +
> > +#define cdns_mhdp_mailbox_recv_header(__mhdp, __module_id,
> __opcode,
> > +__req_size) \ ({ \
> > + u32 mbox_size, i; \
> > + u8 header[4]; \
> > + int ret; \
> > +\
> > + do { \
> > + /* read the header of the message */ \
> > + for (i = 0; i < sizeof(header); i++) { \
> > + ret = cdns_mhdp_mailbox_read(__mhdp); \
> > + if (ret < 0) \
> > + break; \ \
> > + header[i] = ret; \
> > + } \
> > +\
> > + mbox_size = get_unaligned_be16(header + 2); \ \
> > + if ((__opcode) != header[0] || (__module_id) != header[1]
> || \
> > + (__req_size) != mbox_size) { \
> > + /* If the message in mailbox is not what we
> want, we need to
> > + * clear the mailbox by reading its contents. */
> \
> > + for (i = 0; i < mbox_size; i++) \
> > + if (cdns_mhdp_mailbox_read(__mhdp)
> < 0) \
> > + break; \ \
> > + ret = -EINVAL; \
> > + } \
> > +\
> > + ret = 0; \
> > +\
> > + } while (0); \
> > +\
> > + ret; \
> > +})
> > +
> > +#define cdns_mhdp_mailbox_recv_data(mhdp, buff, buff_size) \ ({ \
> > + u32 i; \
> > + int ret; \
> > +\
> > + do { \
> > + for (i = 0; i < buff_size; i++) { \
> > + ret = cdns_mhdp_mailbox_read(mhdp); \
> > + if (ret < 0) \
> > + break; \ \
> > + ((u8 *)buff)[i] = ret; \
> > + } \
> > +\
> > + ret = 0; \
> > +\
> > + } while (0); \
> > +\
> > + ret; \
> > +})
> > +
> > +#define cdns_mhdp_mailbox_send(mhdp, module_id, opcode, size,
> > +message) \ ({ \
> > + u8 header[4]; \
> > + int ret, i; \
> > +\
> > + header[0] = opcode; \
> > + header[1] = module_id; \
> > + put_unaligned_be16(size, header + 2); \ \
> > + do { \
> > + for (i = 0; i < sizeof(header); i++) { \
> > + ret = cdns_mhdp_mailbox_write(mhdp,
> header[i]); \
> > + if (ret < 0) \
> > + break; \
> > + } \
> > +\
> > + for (i = 0; i < size; i++) { \
> > + ret = cdns_mhdp_mailbox_write(mhdp, ((u8
> *)message)[i]); \
> > + if (ret < 0) \
> > + break;; \
> > + } \
> > + ret = 0; \
> > + } while (0); \
> > +\
> > + ret; \
> > +})
> > +
> > +#define cdns_mhdp_reg_read(mhdp, addr, value) \ ({ \
> > + u8 msg[4], resp[8]; \
> > + int ret; \
> > +\
> > + put_unaligned_be32(addr, msg); \ \
> > + mutex_lock(&mhdp->mbox_mutex); \ \
> > + do { \
> > + ret = cdns_mhdp_mailbox_send(mhdp,
> MB_MODULE_ID_GENERAL, \
> > +
> GENERAL_REGISTER_READ, \
> > + sizeof(msg), msg); \
> > + if (ret < 0) \
> > + break; \
> > +\
> > + ret = cdns_mhdp_mailbox_recv_header(mhdp,
> MB_MODULE_ID_GENERAL, \
> > +
> GENERAL_REGISTER_READ, \
> > + sizeof(resp));
> \
> > + if (ret < 0) \
> > + break; \
> > +\
> > + ret = cdns_mhdp_mailbox_recv_data(mhdp, resp,
> sizeof(resp)); \
> > + if (ret < 0) \
> > + break; \
> > +\
> > + /* Returned address value should be the same as
> requested */ \
> > + if (memcmp(msg, resp, sizeof(msg))) { \
> > + ret = -EINVAL; \
> > + break; \
> > + } \
> > +\
> > + *((u32 *)value) = get_unaligned_be32(resp + 4); \
> > + ret = 0; \
> > + } while (0); \
> > +\
> > + mutex_unlock(&mhdp->mbox_mutex); \
> > + if (ret < 0) { \
> > + dev_err(mhdp->dev, "Failed to read register\n"); \
> > + *((u32 *)value) = 0; \
> > + } \
> > +\
> > + ret; \
> > +})
> > +
> > +#define cdns_mhdp_reg_write(mhdp, addr, val) \ ({ \
> > + u8 msg[8]; \
> > + int ret; \
> > +\
> > + put_unaligned_be32(addr, msg); \
> > + put_unaligned_be32(val, msg + 4); \ \
> > + mutex_lock(&mhdp->mbox_mutex); \ \
> > + ret = cdns_mhdp_mailbox_send(mhdp, MB_MODULE_ID_GENERAL,
> \
> > + GENERAL_REGISTER_WRITE,
> > +sizeof(msg), msg); \ \
> > + mutex_unlock(&mhdp->mbox_mutex); \ \
> > + ret; \
> > +})
> > +
> > +#define cdns_mhdp_reg_write_bit(mhdp, addr, start_bit, bits_no, val)
> > +\ ({ \
> > + u8 field[8]; \
> > + int ret; \
> > +\
> > + put_unaligned_be16(addr, field); \
> > + field[2] = start_bit; \
> > + field[3] = bits_no; \
> > + put_unaligned_be32(val, field + 4); \ \
> > + mutex_lock(&mhdp->mbox_mutex); \ \
> > + ret = cdns_mhdp_mailbox_send(mhdp, MB_MODULE_ID_DP_TX, \
> > + DPTX_WRITE_FIELD,
> sizeof(field),
> > +field); \ \
> > + mutex_unlock(&mhdp->mbox_mutex); \ \
> > + ret; \
> > +})
> > +
> > +#endif
>