[PATCH v2 4/8] drm: xlnx: zynqmp_dpsub: Minimize usage of global flag

[Klymenko, Anatoliy]

Hi Laurent,

Thank you for the review.

> -----Original Message-----
> From: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> Sent: Monday, March 18, 2024 5:13 PM
> To: Klymenko, Anatoliy <Anatoliy.Klymenko at amd.com>
> Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>; Maxime Ripard
> <mripard at kernel.org>; Thomas Zimmermann <tzimmermann at suse.de>; David
> Airlie <airlied at gmail.com>; Daniel Vetter <daniel at ffwll.ch>; Simek, Michal
> <michal.simek at amd.com>; Andrzej Hajda <andrzej.hajda at intel.com>; Neil
> Armstrong <neil.armstrong at linaro.org>; Robert Foss <rfoss at kernel.org>; Jonas
> Karlman <jonas at kwiboo.se>; Jernej Skrabec <jernej.skrabec at gmail.com>; Rob
> Herring <robh+dt at kernel.org>; Krzysztof Kozlowski
> <krzysztof.kozlowski+dt at linaro.org>; Conor Dooley <conor+dt at kernel.org>;
> Mauro Carvalho Chehab <mchehab at kernel.org>; dri-
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> kernel at vger.kernel.org; devicetree at vger.kernel.org; linux-
> media at vger.kernel.org
> Subject: Re: [PATCH v2 4/8] drm: xlnx: zynqmp_dpsub: Minimize usage of global
> flag
> 
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> 
> 
> Hi Anatoliy,
> 
> Thank you for the patch.
> 
> On Tue, Mar 12, 2024 at 05:55:01PM -0700, Anatoliy Klymenko wrote:
> > Avoid usage of global zynqmp_dpsub.dma_enabled flag in DPSUB layer
> > context. This flag signals whether the driver runs in DRM CRTC or DRM
> > bridge mode, assuming that all display layers share the same live or
> > non-live mode of operation. Using per-layer mode instead of global
> > flag will siplify future support of the hybrid scenario.
> 
> s/siplify/simplify/
> 
> > Signed-off-by: Anatoliy Klymenko <anatoliy.klymenko at amd.com>
> > ---
> >  drivers/gpu/drm/xlnx/zynqmp_disp.c | 11 ++++-------
> >  1 file changed, 4 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/xlnx/zynqmp_disp.c
> > b/drivers/gpu/drm/xlnx/zynqmp_disp.c
> > index af851190f447..dd48fa60fa9a 100644
> > --- a/drivers/gpu/drm/xlnx/zynqmp_disp.c
> > +++ b/drivers/gpu/drm/xlnx/zynqmp_disp.c
> > @@ -975,7 +975,7 @@ void zynqmp_disp_layer_disable(struct
> > zynqmp_disp_layer *layer)  {
> >       unsigned int i;
> >
> > -     if (layer->disp->dpsub->dma_enabled) {
> > +     if (layer->mode == ZYNQMP_DPSUB_LAYER_NONLIVE) {
> >               for (i = 0; i < layer->drm_fmt->num_planes; i++)
> >                       dmaengine_terminate_sync(layer->dmas[i].chan);
> >       }
> > @@ -1001,7 +1001,7 @@ void zynqmp_disp_layer_set_format(struct
> > zynqmp_disp_layer *layer,
> >
> >       zynqmp_disp_avbuf_set_format(layer->disp, layer,
> > layer->disp_fmt);
> >
> > -     if (!layer->disp->dpsub->dma_enabled)
> > +     if (layer->mode == ZYNQMP_DPSUB_LAYER_LIVE)
> >               return;
> >
> >       /*
> > @@ -1039,7 +1039,7 @@ int zynqmp_disp_layer_update(struct
> zynqmp_disp_layer *layer,
> >       const struct drm_format_info *info = layer->drm_fmt;
> >       unsigned int i;
> >
> > -     if (!layer->disp->dpsub->dma_enabled)
> > +     if (layer->mode == ZYNQMP_DPSUB_LAYER_LIVE)
> >               return 0;
> 
> The above changes look nice.
> 
> >
> >       for (i = 0; i < info->num_planes; i++) { @@ -1089,7 +1089,7 @@
> > static void zynqmp_disp_layer_release_dma(struct zynqmp_disp *disp,  {
> >       unsigned int i;
> >
> > -     if (!layer->info || !disp->dpsub->dma_enabled)
> > +     if (!layer->info)
> 
> This, however, doesn't seem right, as this function is called unconditionally from
> the remove path. The change below seems weird too.
> If I'm missing something, it should at least be explained in the commit message.
> 

Actually, this whole condition should be removed, as now we're setting layer.info for all types of layers. On top of that, we're setting the number of DMA channels to zero for the live layers, which in turn prevents any DMA channel initialization or release. You are right - that probably should be mentioned explicitly in the commit message. I'll update it.

> >               return;
> >
> >       for (i = 0; i < layer->info->num_channels; i++) { @@ -1132,9
> > +1132,6 @@ static int zynqmp_disp_layer_request_dma(struct zynqmp_disp
> *disp,
> >       unsigned int i;
> >       int ret;
> >
> > -     if (!disp->dpsub->dma_enabled)
> > -             return 0;
> > -
> >       for (i = 0; i < layer->info->num_channels; i++) {
> >               struct zynqmp_disp_layer_dma *dma = &layer->dmas[i];
> >               char dma_channel_name[16];
> >
> 
> --
> Regards,
> 
> Laurent Pinchart

Thank you,
Anatoliy