Re: [PATCH] Revert "media: vsp1: Add underrun debug print"
From: Kieran Bingham
Date: Tue Nov 11 2025 - 07:07:27 EST
Quoting Tomi Valkeinen (2025-09-10 08:26:43)
> This reverts commit 1dc30075fb0fe02b74b1ea7fd1c1c734a89f1448.
>
> There have been reports of lots of underruns happening on earlier
> generation SoCs (M3, E3) with display use cases, e.g.:
>
> vsp1 fea28000.vsp: Underrun occurred at WPF0 (total underruns 1)
>
> but the display still working fine, and reverting the above commit,
> which added underrun prints, makes the prints go away (obviously).
>
> I made some tests on a remote M3, with no display connected, and I can
> confirm that there seem to be a single underrun report quite often when
> enabling a display, and an underrun flood when using interlace display
> modes.
>
> E3 does not have interlace display support as far as I can see, so the
> interlace issue does not concern it.
>
> Debugging display issues remotely without a display is quite
> challenging, and I did not find any issues in the code, nor could I find
> a way to stop the underruns by twiddling with the related registers.
>
> My pure guess is that the single underruns occurring when starting the
> display hint at either a startup sequence issue, or some kind of initial
> fifo loading issue. The interlace underruns hint at a bigger
> misconfiguration, but as the display works fine, the issue might be just
> an underrun at the start of the frame and the HW quickly catching up, or
> at the end of the frame, where one block in the pipeline expects more
> data but the previous block has already stopped (so maybe a misconfig
> between using interlaced height vs progressive height?).
>
> But at the moment I have no solution to this, and as the displays work
> fine, I think it makes sense to just revert the print.
Is there any value in instead 'ignoring' any underruns if say the frame
count is < 5 to ignore startup underruns, and keep it as an active print
if something causes underruns later once the pipeline is established?
But maybe that doesn't change much - and if there's no current perceived
issue
Anyway, I don't object to this revert. It's low impact and it's only
undoing 'your' work so no one else will complain :D
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@xxxxxxxxxxxxxxxx>
>
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
> ---
> drivers/media/platform/renesas/vsp1/vsp1_drm.c | 3 ---
> drivers/media/platform/renesas/vsp1/vsp1_drv.c | 11 +----------
> drivers/media/platform/renesas/vsp1/vsp1_pipe.h | 2 --
> drivers/media/platform/renesas/vsp1/vsp1_regs.h | 2 --
> 4 files changed, 1 insertion(+), 17 deletions(-)
>
> diff --git a/drivers/media/platform/renesas/vsp1/vsp1_drm.c b/drivers/media/platform/renesas/vsp1/vsp1_drm.c
> index 15d266439564..b8f211db16fc 100644
> --- a/drivers/media/platform/renesas/vsp1/vsp1_drm.c
> +++ b/drivers/media/platform/renesas/vsp1/vsp1_drm.c
> @@ -721,9 +721,6 @@ int vsp1_du_setup_lif(struct device *dev, unsigned int pipe_index,
> return 0;
> }
>
> - /* Reset the underrun counter */
> - pipe->underrun_count = 0;
> -
> drm_pipe->width = cfg->width;
> drm_pipe->height = cfg->height;
> pipe->interlaced = cfg->interlaced;
> diff --git a/drivers/media/platform/renesas/vsp1/vsp1_drv.c b/drivers/media/platform/renesas/vsp1/vsp1_drv.c
> index b8d06e88c475..68e92d3c5915 100644
> --- a/drivers/media/platform/renesas/vsp1/vsp1_drv.c
> +++ b/drivers/media/platform/renesas/vsp1/vsp1_drv.c
> @@ -47,8 +47,7 @@
>
> static irqreturn_t vsp1_irq_handler(int irq, void *data)
> {
> - u32 mask = VI6_WPF_IRQ_STA_DFE | VI6_WPF_IRQ_STA_FRE |
> - VI6_WPF_IRQ_STA_UND;
> + u32 mask = VI6_WPF_IRQ_STA_DFE | VI6_WPF_IRQ_STA_FRE;
> struct vsp1_device *vsp1 = data;
> irqreturn_t ret = IRQ_NONE;
> unsigned int i;
> @@ -63,14 +62,6 @@ static irqreturn_t vsp1_irq_handler(int irq, void *data)
> status = vsp1_read(vsp1, VI6_WPF_IRQ_STA(i));
> vsp1_write(vsp1, VI6_WPF_IRQ_STA(i), ~status & mask);
>
> - if ((status & VI6_WPF_IRQ_STA_UND) && wpf->entity.pipe) {
> - wpf->entity.pipe->underrun_count++;
> -
> - dev_warn_ratelimited(vsp1->dev,
> - "Underrun occurred at WPF%u (total underruns %u)\n",
> - i, wpf->entity.pipe->underrun_count);
> - }
> -
> if (status & VI6_WPF_IRQ_STA_DFE) {
> vsp1_pipeline_frame_end(wpf->entity.pipe);
> ret = IRQ_HANDLED;
> diff --git a/drivers/media/platform/renesas/vsp1/vsp1_pipe.h b/drivers/media/platform/renesas/vsp1/vsp1_pipe.h
> index 7f623b8cbe5c..9cc2f1646b00 100644
> --- a/drivers/media/platform/renesas/vsp1/vsp1_pipe.h
> +++ b/drivers/media/platform/renesas/vsp1/vsp1_pipe.h
> @@ -137,8 +137,6 @@ struct vsp1_pipeline {
>
> unsigned int partitions;
> struct vsp1_partition *part_table;
> -
> - u32 underrun_count;
> };
>
> void vsp1_pipeline_reset(struct vsp1_pipeline *pipe);
> diff --git a/drivers/media/platform/renesas/vsp1/vsp1_regs.h b/drivers/media/platform/renesas/vsp1/vsp1_regs.h
> index 10cfbcd1b6e0..188d26289714 100644
> --- a/drivers/media/platform/renesas/vsp1/vsp1_regs.h
> +++ b/drivers/media/platform/renesas/vsp1/vsp1_regs.h
> @@ -32,12 +32,10 @@
> #define VI6_STATUS_SYS_ACT(n) BIT((n) + 8)
>
> #define VI6_WPF_IRQ_ENB(n) (0x0048 + (n) * 12)
> -#define VI6_WPF_IRQ_ENB_UNDE BIT(16)
> #define VI6_WPF_IRQ_ENB_DFEE BIT(1)
> #define VI6_WPF_IRQ_ENB_FREE BIT(0)
>
> #define VI6_WPF_IRQ_STA(n) (0x004c + (n) * 12)
> -#define VI6_WPF_IRQ_STA_UND BIT(16)
> #define VI6_WPF_IRQ_STA_DFE BIT(1)
> #define VI6_WPF_IRQ_STA_FRE BIT(0)
>
>
> ---
> base-commit: 76eeb9b8de9880ca38696b2fb56ac45ac0a25c6c
> change-id: 20250908-rcar-vsp-underrun-revert-f3e64612c62d
>
> Best regards,
> --
> Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
>