Hi Eugeniu, On Thu, Apr 21, 2022 at 06:12:59PM +0200, Eugeniu Rosca wrote: > Dear Uli, > Dear Laurent, > Dear Renesas community, > > On Mo, Mai 30, 2016 at 06:00:13 +0200, Ulrich Hecht wrote: > > This patch changes to VSPD hardware recommended value. > > Purpose is highest pixel clock without underruns. > > In the default R-Car Linux BSP config this value is > > wrong and therefore there are many underruns. > > > > Signed-off-by: Takashi Saito <takashi.saitou.ry@xxxxxxxxxxx> > > Signed-off-by: Koji Matsuoka <koji.matsuoka.xm@xxxxxxxxxxx> > > Signed-off-by: Ulrich Hecht <ulrich.hecht+renesas@xxxxxxxxx> > > Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx> > > --- > > drivers/media/platform/vsp1/vsp1_lif.c | 6 +++--- > > 1 file changed, 3 insertions(+), 3 deletions(-) > > Apologize for reviving this very old thread. > > We've been struggling with very rare and difficult to reproduce > display flickering occurrences and, after significant amount of > troubleshooting and debugging, with some support from Renesas, > we've been able to identify that those flicker issues are caused > by VSPD underruns. > > What we've also learned is that one possible root-cause for seeing > VSPD underruns is having wrong QoS settings in DBSC (set in ATF). > > What was particularly helpful in identifying the underruns themselves > is Renesas BSP commit [1], whose discussions we were unable to track > on linux-renesas-soc LKML. > > My question is very simple. Since the meat of the Renesas patch [1] > is basically a printk in the interrupt context and an array storing > the total number of underruns occurred since startup, would you be > willing to review the refactored version of this patch on LKML? > > In that case, we'll definitely invest some time to upstream it. Absolutely ! I'm all for helping debugging. > Thank you for your attention and feedback. > > [1] https://github.com/renesas-rcar/linux-bsp/commit/12ea79975a10f > ("v4l: vsp1: Add underrun debug messege option") -- Regards, Laurent Pinchart
