Re: [PATCH v3 12/38] drm/msm/dp: introduce max_streams for DP controller MST support

[Dmitry Baryshkov]

On Mon, Mar 30, 2026 at 05:57:13PM +0800, Yongxing Mou wrote:
> 
> 
> On 8/26/2025 1:42 AM, Dmitry Baryshkov wrote:
> > On Mon, Aug 25, 2025 at 10:15:58PM +0800, Yongxing Mou wrote:
> > > From: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
> > > 
> > > Introduce the `mst_streams` field in each DP controller descriptor to
> > > specify the number of supported MST streams. Most platforms support 2 or
> > > 4 MST streams, while platforms without MST support default to a single
> > > stream (`DEFAULT_STREAM_COUNT = 1`).
> > > 
> > > This change also accounts for platforms with asymmetric stream support,
> > > e.g., DP0 supporting 4 streams and DP1 supporting 2.
> > 
> > How?
> > 
> Each DP controller have it own msm_dp_desc ...

Why do you need to mention it?

> > > 
> > > Signed-off-by: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
> > > Signed-off-by: Yongxing Mou <yongxing.mou@xxxxxxxxxxxxxxxx>
> > > ---
> > >   drivers/gpu/drm/msm/dp/dp_display.c | 21 +++++++++++++++++++++
> > >   drivers/gpu/drm/msm/dp/dp_display.h |  1 +
> > >   2 files changed, 22 insertions(+)
> > > 
> > > diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> > > index 78d932bceb581ee54116926506b1025bd159108f..a8477a0a180137f15cbb1401c3964636aa32626c 100644
> > > --- a/drivers/gpu/drm/msm/dp/dp_display.c
> > > +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> > > @@ -33,6 +33,7 @@ module_param(psr_enabled, bool, 0);
> > >   MODULE_PARM_DESC(psr_enabled, "enable PSR for eDP and DP displays");
> > >   #define HPD_STRING_SIZE 30
> > > +#define DEFAULT_STREAM_COUNT 1
> > >   enum {
> > >   	ISR_DISCONNECTED,
> > > @@ -52,6 +53,7 @@ struct msm_dp_display_private {
> > >   	bool core_initialized;
> > >   	bool phy_initialized;
> > >   	bool audio_supported;
> > > +	bool mst_supported;
> > 
> > Why do we need the separate boot field here? Isn't it enough to check the max_stream?
> > 
> If remove mst_supported, condition "mst_streams > 1" will appear in multiple
> places.

And so what? If you want, extract the function, but don't add
duplicating data.

> > >   	struct drm_device *drm_dev;

-- 
With best wishes
Dmitry