On Mon, Aug 25, 2025 at 10:15:58PM +0800, Yongxing Mou wrote:
> From: Abhinav Kumar <quic_abhin...@quicinc.com>
>
> 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?
>
> Signed-off-by: Abhinav Kumar <quic_abhin...@quicinc.com>
> Signed-off-by: Yongxing Mou <yongxing....@oss.qualcomm.com>
> ---
> 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?
>
> struct drm_device *drm_dev;
>
> @@ -84,12 +86,15 @@ struct msm_dp_display_private {
>
> void __iomem *p0_base;
> size_t p0_len;
> +
> + int max_stream;
> };
>
> struct msm_dp_desc {
> phys_addr_t io_start;
> unsigned int id;
> bool wide_bus_supported;
> + int mst_streams;
> };
>
> static const struct msm_dp_desc msm_dp_desc_sa8775p[] = {
> @@ -1213,6 +1218,15 @@ static int msm_dp_display_get_io(struct
> msm_dp_display_private *display)
> return 0;
> }
>
> +int msm_dp_get_mst_max_stream(struct msm_dp *msm_dp_display)
> +{
> + struct msm_dp_display_private *dp;
> +
> + dp = container_of(msm_dp_display, struct msm_dp_display_private,
> msm_dp_display);
> +
> + return dp->max_stream;
> +}
> +
> static int msm_dp_display_probe(struct platform_device *pdev)
> {
> int rc = 0;
> @@ -1239,6 +1253,13 @@ static int msm_dp_display_probe(struct platform_device
> *pdev)
> dp->msm_dp_display.is_edp =
> (dp->msm_dp_display.connector_type == DRM_MODE_CONNECTOR_eDP);
> dp->hpd_isr_status = 0;
> + dp->max_stream = DEFAULT_STREAM_COUNT;
Just use 1 it's not that magic to define it.
> + dp->mst_supported = FALSE;
> +
> + if (desc->mst_streams > DEFAULT_STREAM_COUNT) {
> + dp->max_stream = desc->mst_streams;
> + dp->mst_supported = TRUE;
> + }
>
> rc = msm_dp_display_get_io(dp);
> if (rc)
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.h
> b/drivers/gpu/drm/msm/dp/dp_display.h
> index
> 37c6e87db90ce951274cdae61f26d76dc9ef3840..7727cf325a89b4892d2370a5616c4fa76fc88485
> 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.h
> +++ b/drivers/gpu/drm/msm/dp/dp_display.h
> @@ -29,6 +29,7 @@ struct msm_dp {
> bool psr_supported;
> };
>
> +int msm_dp_get_mst_max_stream(struct msm_dp *msm_dp_display);
> int msm_dp_display_get_modes(struct msm_dp *msm_dp_display);
> bool msm_dp_display_check_video_test(struct msm_dp *msm_dp_display);
> int msm_dp_display_get_test_bpp(struct msm_dp *msm_dp_display);
>
> --
> 2.34.1
>
--
With best wishes
Dmitry
