Thanks Charlton for the patch.
I think in general it is a good idea to log this when the max rate is
dropped to HBR3 for SST case.
Please find my comments below,
On Thu, Feb 29, 2024 at 11:49 PM Charlton Lin <charlton.lin@xxxxxxxxx> wrote:
>
> Driver currently limits link rate up to HBR3 in SST mode. Log a
> message with monitor vendor, product id, and MSTM_CAP to
> help understand what monitors are being downgraded by this limit.
>
> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> Cc: Khaled Almahallawy <khaled.almahallawy@xxxxxxxxx>
> Cc: Sean Paul <seanpaul@xxxxxxxxxxxx>
> Signed-off-by: Charlton Lin <charlton.lin@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/intel_dp.c | 19 +++++++++++++++++++
> 1 file changed, 19 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 6ece2c563c7a..0b2d6d88fd37 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -2437,6 +2437,25 @@ intel_dp_compute_link_config(struct intel_encoder *encoder,
> false,
> &limits);
>
> + if (intel_dp_max_common_rate(intel_dp) > limits.max_rate) {
> + u8 mstm_cap;
> + u32 panel_id = drm_edid_get_panel_id(&intel_dp->aux.ddc);
> + char vend[4];
> + u16 product_id;
> +
> + drm_dbg_kms(&i915->drm,
> + "Limiting LR from max common rate %d to %d\n",
We dont use LR acronym anywhere in the kernel for link rate, just say
link rate here.
Also I think would be good to log the reason why we are dropping this
to HBR3 or add a comment with a Todo
for this
Manasi
> + intel_dp_max_common_rate(intel_dp), limits.max_rate);
> +
> + drm_edid_decode_panel_id(panel_id, vend, &product_id);
> +
> + if (intel_dp->dpcd[DP_DPCD_REV] >= DP_DPCD_REV_12 &&
> + drm_dp_dpcd_readb(&intel_dp->aux, DP_MSTM_CAP, &mstm_cap) == 1)
> + drm_dbg_kms(&i915->drm,
> + "Manufacturer=%s Model=%x Sink MSTM_CAP=%x\n",
> + vend, product_id, mstm_cap);
> + }
> +
> if (!dsc_needed) {
> /*
> * Optimize for slow and wide for everything, because there are some
> --
> 2.25.1
>
