Re: [PATCH v2 1/5] media: venus: add a routine to reset ARM9

From: Vikash Garodia
Date: Wed Jul 04 2018 - 04:35:40 EST


Hi Stanimir,

Thanks for the review.

On 2018-06-02 03:45, Stanimir Varbanov wrote:
Hi Vikash,

On 1.06.2018 23:26, Vikash Garodia wrote:
Add a new routine to reset the ARM9 and brings it
out of reset. This is in preparation to add PIL
functionality in venus driver.

please squash this patch with 4/5. I don't see a reason to add a
function which is not used. Shouldn't this produce gcc warnings?

Will squash the api definition with the patch using it.


Signed-off-by: Vikash Garodia <vgarodia@xxxxxxxxxxxxxx>
---
drivers/media/platform/qcom/venus/firmware.c | 26 ++++++++++++++++++++++++
drivers/media/platform/qcom/venus/hfi_venus_io.h | 5 +++++
2 files changed, 31 insertions(+)

diff --git a/drivers/media/platform/qcom/venus/firmware.c b/drivers/media/platform/qcom/venus/firmware.c
index 521d4b3..7d89b5a 100644
--- a/drivers/media/platform/qcom/venus/firmware.c
+++ b/drivers/media/platform/qcom/venus/firmware.c
@@ -14,6 +14,7 @@
#include <linux/device.h>
#include <linux/firmware.h>
+#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/io.h>
#include <linux/of.h>
@@ -22,11 +23,36 @@
#include <linux/sizes.h>
#include <linux/soc/qcom/mdt_loader.h>
+#include "core.h"
#include "firmware.h"
+#include "hfi_venus_io.h"
#define VENUS_PAS_ID 9
#define VENUS_FW_MEM_SIZE (6 * SZ_1M)
+static void venus_reset_hw(struct venus_core *core)

can we rename this to venus_reset_cpu? reset_hw sounds like we reset
vcodec IPs, so I think we can be more exact here.

+{
+ void __iomem *reg_base = core->base;

just 'base', please.
Ok.

+
+ writel(0, reg_base + WRAPPER_FW_START_ADDR);
+ writel(VENUS_FW_MEM_SIZE, reg_base + WRAPPER_FW_END_ADDR);
+ writel(0, reg_base + WRAPPER_CPA_START_ADDR);
+ writel(VENUS_FW_MEM_SIZE, reg_base + WRAPPER_CPA_END_ADDR);
+ writel(0x0, reg_base + WRAPPER_CPU_CGC_DIS);
+ writel(0x0, reg_base + WRAPPER_CPU_CLOCK_CONFIG);
+
+ /* Make sure all register writes are committed. */
+ mb();

the comment says "register writes" hence shouldn't this be wmb? Also
if we are going to have explicit memory barrier why not use
writel_relaxed?
+
+ /*
+ * Need to wait 10 cycles of internal clocks before bringing ARM9

Do we know what is the minimum frequency of the internal ARM9 clocks?
I.e does 1us is enough for all venus versions.

ARM9 is yet not brought out of reset at this point. Sleep might be added
to ensure that the register writes are completed. But as Bjorn commented,
only way to ensure registers are written is to read them back. I do not have
proper justification of sleep as this code was used for many chipset bringup.
I can try by removing the sleep and if goes well, we can live without it.

+ * out of reset.
+ */
+ udelay(1);
+
+ /* Bring Arm9 out of reset */

ARM9

+ writel_relaxed(0, reg_base + WRAPPER_A9SS_SW_RESET);

in my opinion we should have a wmb here too
I guess if sleep is removed, we will be left with only the above instruction.
so no need to ensure the access order.

regards,
Stan