Re: [PATCH v5 0/7] Add AMD ISP4 driver

[Sultan Alsawaf <sultan@kerneltoast.com>]

On Tue, Nov 11, 2025 at 05:58:10PM +0800, Du, Bin wrote:
> 
> On 11/11/2025 5:05 PM, Sultan Alsawaf wrote:
> 
> > On Mon, Nov 10, 2025 at 05:46:28PM +0800, Du, Bin wrote:
> > > Thank you, Sultan, for your time, big effort, and constant support.
> > > Apologies for my delayed reply for being occupied a little with other
> > > matters.
> > > 
> > > On 11/10/2025 4:33 PM, Sultan Alsawaf wrote:
> > > > Hi Bin,
> > > > 
> > > > On Wed, Nov 05, 2025 at 01:25:58AM -0800, Sultan Alsawaf wrote:
> > > > > Hi Bin,
> > > > > 
> > > > > To expedite review, I've attached a patch containing a bunch of fixes I've made
> > > > > on top of v5. Most of my changes should be self-explanatory; feel free to ask
> > > > > further about specific changes if you have any questions.
> > > > > 
> > > > > I haven't had a chance to review all of the v4 -> v5 changes yet, but I figured
> > > > > I should send what I've got so far.
> > > > > 
> > > > > FYI, there is a regression in isp4if_dequeue_buffer() where the bufq lock isn't
> > > > > protecting the list_del() anymore. I also checked the compiler output when using
> > > > > guard() versus scoped_guard() in that function and there is no difference:
> > > > > 
> > > > >     sha1sum:
> > > > >     5652a0306da22ea741d80a9e03a787d0f71758a8  isp4_interface.o // guard()
> > > > >     5652a0306da22ea741d80a9e03a787d0f71758a8  isp4_interface.o // scoped_guard()
> > > > > 
> > > > > So guard() should be used there again, which I've done in my patch.
> > > > > 
> > > > > I also have a few questions:
> > > > > 
> > > > > 1. Does ISP FW provide a register interface to disable the IRQ? If so, it is
> > > > >      faster to use that than using disable_irq_nosync() to disable the IRQ from
> > > > >      the CPU's side.
> > > > > 
> > > > > 2. When the IRQ is re-enabled in isp4sd_fw_resp_func(), is there anything
> > > > >      beforehand to mask all pending interrupts from the ISP so that there isn't a
> > > > >      bunch of stale interrupts firing as soon the IRQ is re-enabled?
> > > > > 
> > > > > 3. Is there any risk of deadlock due to the stream kthread racing with the ISP
> > > > >      when the ISP posts a new response _after_ the kthread determines there are no
> > > > >      more new responses but _before_ the enable_irq() in isp4sd_fw_resp_func()?
> > > > > 
> > > > > 4. Why are some lines much longer than before? It seems inconsistent that now
> > > > >      there is a mix of several lines wrapped to 80 cols and many lines going
> > > > >      beyond 80 cols. And there are multiple places where code is wrapped before
> > > > >      reaching 80 cols even with lots of room left, specifically for cases where it
> > > > >      wouldn't hurt readability to put more characters onto each line.
> > > > 
> > > > I've attached a new, complete patch of changes to apply on top of v5. You may
> > > > ignore the incomplete patch from my previous email and use the new one instead.
> > > > 
> > > > I made many changes and also answered questions 1-3 myself.
> > > > 
> > > > Please apply this on top of v5 and let me know if you have any questions.
> > > > 
> > > 
> > > Sure, will review, apply and test your patch accordingly. Your contribution
> > > is greatly appreciated, will let you know if there is any question or
> > > problem.
> > > 
> > > > BTW, I noticed a strange regression in v5 even without any of my changes: every
> > > > time you use cheese after using it one time, the video will freeze after 30-60
> > > > seconds with this message printed to dmesg:
> > > >     [ 2032.716559] amd_isp_capture amd_isp_capture: -><- fail respid unknown respid(0x30002)
> > > > 
> > > > And the video never unfreezes. I haven't found the cause for the regression yet;
> > > > can you try to reproduce it?
> > > > 
> > > 
> > > Really weird, we don't see this issue either in dev or QA test. Is it 100%
> > > reproducible and any other fail or err in the log?
> > 
> > Yes, it's 100% reproducible. There's no other message in dmesg, only that one.
> > 
> > Sometimes there is a stop stream error when I close cheese after it froze:
> > 
> >    [  656.540307] amd_isp_capture amd_isp_capture: fail to disable stream
> >    [  657.046633] amd_isp_capture amd_isp_capture: fail to stop steam
> >    [  657.047224] amd_isp_capture amd_isp_capture: disabling streaming failed (-110)
> > 
> > When I revert to v4 I cannot reproduce it at all. It seems to be something in
> > v4 -> v5 that is not fixed by any of my changes.
> > 
> 
> Hi Sultan, could you please try following modifications on top of v5 to see
> if it helps?
> 
> diff --git a/drivers/media/platform/amd/isp4/isp4_fw_cmd_resp.h
> b/drivers/media/platform/amd/isp4/isp4_fw_cmd_resp.h
> index 39c2265121f9..d571b3873edb 100644
> --- a/drivers/media/platform/amd/isp4/isp4_fw_cmd_resp.h
> +++ b/drivers/media/platform/amd/isp4/isp4_fw_cmd_resp.h
> @@ -97,7 +97,7 @@
> 
> #define ADDR_SPACE_TYPE_GPU_VA          4
> 
> -#define FW_MEMORY_POOL_SIZE             (200 * 1024 * 1024)
> +#define FW_MEMORY_POOL_SIZE             (100 * 1024 * 1024)
> 
> /*
>   * standard ISP mipicsi=>isp
> diff --git a/drivers/media/platform/amd/isp4/isp4_subdev.c
> b/drivers/media/platform/amd/isp4/isp4_subdev.c
> index 248d10076ae8..acbc80aa709e 100644
> --- a/drivers/media/platform/amd/isp4/isp4_subdev.c
> +++ b/drivers/media/platform/amd/isp4/isp4_subdev.c
> @@ -697,7 +697,7 @@ static int isp4sd_stop_resp_proc_threads(struct
> isp4_subdev *isp_subdev)
>         return 0;
> }
> 
> -static int isp4sd_pwroff_and_deinit(struct isp4_subdev *isp_subdev)
> +static int isp4sd_pwroff_and_deinit(struct isp4_subdev *isp_subdev, bool
> irq_enabled)
> {
>         struct isp4sd_sensor_info *sensor_info = &isp_subdev->sensor_info;
>         unsigned int perf_state = ISP4SD_PERFORMANCE_STATE_LOW;
> @@ -716,8 +716,9 @@ static int isp4sd_pwroff_and_deinit(struct isp4_subdev
> *isp_subdev)
>                 return 0;
>         }
> 
> -       for (int i = 0; i < ISP4SD_MAX_FW_RESP_STREAM_NUM; i++)
> -               disable_irq(isp_subdev->irq[i]);
> +       if (irq_enabled)
> +               for (int i = 0; i < ISP4SD_MAX_FW_RESP_STREAM_NUM; i++)
> +                       disable_irq(isp_subdev->irq[i]);
> 
>         isp4sd_stop_resp_proc_threads(isp_subdev);
>         dev_dbg(dev, "isp_subdev stop resp proc streads suc");
> @@ -813,7 +814,7 @@ static int isp4sd_pwron_and_init(struct isp4_subdev
> *isp_subdev)
> 
>         return 0;
> err_unlock_and_close:
> -       isp4sd_pwroff_and_deinit(isp_subdev);
> +       isp4sd_pwroff_and_deinit(isp_subdev, false);
>         return -EINVAL;
> }
> 
> @@ -985,7 +986,7 @@ static int isp4sd_set_power(struct v4l2_subdev *sd, int
> on)
>         if (on)
>                 return isp4sd_pwron_and_init(isp_subdev);
>         else
> -               return isp4sd_pwroff_and_deinit(isp_subdev);
> +               return isp4sd_pwroff_and_deinit(isp_subdev, true);
> }
> 
> static const struct v4l2_subdev_core_ops isp4sd_core_ops = {

No difference sadly; same symptoms as before. FYI, your email client broke the
patch formatting so I couldn't apply it; it hard wrapped some lines to 80 cols,
replaced tabs with spaces, and removed leading spaces on each context line, so I
had to apply it manually. To confirm I applied it correctly, here is my diff:

diff --git a/drivers/media/platform/amd/isp4/isp4_fw_cmd_resp.h b/drivers/media/platform/amd/isp4/isp4_fw_cmd_resp.h
index 39c2265121f9..d571b3873edb 100644
--- a/drivers/media/platform/amd/isp4/isp4_fw_cmd_resp.h
+++ b/drivers/media/platform/amd/isp4/isp4_fw_cmd_resp.h
@@ -97,7 +97,7 @@
 
 #define ADDR_SPACE_TYPE_GPU_VA          4
 
-#define FW_MEMORY_POOL_SIZE             (200 * 1024 * 1024)
+#define FW_MEMORY_POOL_SIZE             (100 * 1024 * 1024)
 
 /*
  * standard ISP mipicsi=>isp
diff --git a/drivers/media/platform/amd/isp4/isp4_subdev.c b/drivers/media/platform/amd/isp4/isp4_subdev.c
index 4bd2ebf0f694..500ef0af8a41 100644
--- a/drivers/media/platform/amd/isp4/isp4_subdev.c
+++ b/drivers/media/platform/amd/isp4/isp4_subdev.c
@@ -669,7 +669,7 @@ static int isp4sd_stop_resp_proc_threads(struct isp4_subdev *isp_subdev)
 	return 0;
 }
 
-static int isp4sd_pwroff_and_deinit(struct isp4_subdev *isp_subdev)
+static int isp4sd_pwroff_and_deinit(struct isp4_subdev *isp_subdev, bool irq_enabled)
 {
 	struct isp4sd_sensor_info *sensor_info = &isp_subdev->sensor_info;
 	unsigned int perf_state = ISP4SD_PERFORMANCE_STATE_LOW;
@@ -688,8 +688,9 @@ static int isp4sd_pwroff_and_deinit(struct isp4_subdev *isp_subdev)
 		return 0;
 	}
 
-	for (int i = 0; i < ISP4SD_MAX_FW_RESP_STREAM_NUM; i++)
-		disable_irq(isp_subdev->irq[i]);
+	if (irq_enabled)
+		for (int i = 0; i < ISP4SD_MAX_FW_RESP_STREAM_NUM; i++)
+			disable_irq(isp_subdev->irq[i]);
 
 	isp4sd_stop_resp_proc_threads(isp_subdev);
 	dev_dbg(dev, "isp_subdev stop resp proc streads suc");
@@ -785,7 +786,7 @@ static int isp4sd_pwron_and_init(struct isp4_subdev *isp_subdev)
 
 	return 0;
 err_unlock_and_close:
-	isp4sd_pwroff_and_deinit(isp_subdev);
+	isp4sd_pwroff_and_deinit(isp_subdev, false);
 	return -EINVAL;
 }
 
@@ -957,7 +958,7 @@ static int isp4sd_set_power(struct v4l2_subdev *sd, int on)
 	if (on)
 		return isp4sd_pwron_and_init(isp_subdev);
 	else
-		return isp4sd_pwroff_and_deinit(isp_subdev);
+		return isp4sd_pwroff_and_deinit(isp_subdev, true);
 }
 
 static const struct v4l2_subdev_core_ops isp4sd_core_ops = {

> On the other hand, please also add the patch in amdgpu which sets *bo to
> NULL in isp_kernel_buffer_alloc() which you mentioned in another thread.

Yep, I have been doing all v5 testing with that patch applied. 

BTW, I have verified the IRQ changes are not the cause for the regression; I
tested with IRQs kept enabled all the time and the issue still occurs.

I did observe that ISP stops sending interrupts when the video stream freezes.
And, if I replicate the bug enough times, it seems to permanently break FW until
a full machine reboot. Reloading amd_capture with the v4 driver doesn't recover
the ISP when this happens.

As an improvement to the driver, can we do a hard reset of ISP on driver probe?
I am assuming hardware doesn't need too long to settle after hard reset, maybe
a few hundred milliseconds? This would ensure ISP FW is always in a working
state when the driver is loaded.

Thanks,
Sultan