[PATCH v2 01/38] drm/msm/dp: split msm_dp_panel_read_sink_caps() into two parts and drop panel drm_edid
Dmitry Baryshkov
dmitry.baryshkov at oss.qualcomm.com
Fri Jun 27 12:40:53 UTC 2025
On 27/06/2025 10:49, Yongxing Mou wrote:
>
>
> On 2025/6/25 21:32, Dmitry Baryshkov wrote:
>> On Wed, Jun 25, 2025 at 04:43:55PM +0800, Yongxing Mou wrote:
>>>
>>>
>>> On 2025/6/9 20:41, Dmitry Baryshkov wrote:
>>>> On Mon, Jun 09, 2025 at 08:21:20PM +0800, Yongxing Mou wrote:
>>>>> From: Abhinav Kumar <quic_abhinavk at quicinc.com>
>>>>>
>>>>> In preparation of DP MST where link caps are read for the
>>>>> immediate downstream device and the edid is read through
>>>>
>>>> EDID, not edid. Please review all your patches for up/down case.
>>>>
>>> Got it. Thanks~
>>>>> sideband messaging, split the msm_dp_panel_read_sink_caps() into
>>>>> two parts which read the link parameters and the edid parts
>>>>> respectively. Also drop the panel drm_edid cached as we actually
>>>>> don't need it.
>>>>
>>>> Also => separate change.
>>>>
>>> Got it.
>>>>>
>>>>> Signed-off-by: Abhinav Kumar <quic_abhinavk at quicinc.com>
>>>>> Signed-off-by: Yongxing Mou <quic_yongmou at quicinc.com>
>>>>> ---
>>>>> drivers/gpu/drm/msm/dp/dp_display.c | 13 +++++----
>>>>> drivers/gpu/drm/msm/dp/dp_panel.c | 55 +++++++++++++++++++
>>>>> +-----------------
>>>>> drivers/gpu/drm/msm/dp/dp_panel.h | 6 ++--
>>>>> 3 files changed, 40 insertions(+), 34 deletions(-)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/
>>>>> msm/dp/dp_display.c
>>>>> index
>>>>> 6f05a939ce9e648e9601597155999b6f85adfcff..4a9b65647cdef1ed6c3bb851f93df0db8be977af 100644
>>>>> --- a/drivers/gpu/drm/msm/dp/dp_display.c
>>>>> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
>>>>> @@ -389,7 +389,11 @@ static int
>>>>> msm_dp_display_process_hpd_high(struct msm_dp_display_private *dp)
>>>>> dp->link->lttpr_count = msm_dp_display_lttpr_init(dp, dpcd);
>>>>> - rc = msm_dp_panel_read_sink_caps(dp->panel, connector);
>>>>> + rc = msm_dp_panel_read_link_caps(dp->panel);
>>>>> + if (rc)
>>>>> + goto end;
>>>>> +
>>>>> + rc = msm_dp_panel_read_edid(dp->panel, connector);
>>>>> if (rc)
>>>>> goto end;
>>>>> @@ -720,7 +724,6 @@ static int msm_dp_irq_hpd_handle(struct
>>>>> msm_dp_display_private *dp, u32 data)
>>>>> static void msm_dp_display_deinit_sub_modules(struct
>>>>> msm_dp_display_private *dp)
>>>>> {
>>>>> msm_dp_audio_put(dp->audio);
>>>>> - msm_dp_panel_put(dp->panel);
>>>>> msm_dp_aux_put(dp->aux);
>>>>> }
>>>>> @@ -783,7 +786,7 @@ static int msm_dp_init_sub_modules(struct
>>>>> msm_dp_display_private *dp)
>>>>> rc = PTR_ERR(dp->ctrl);
>>>>> DRM_ERROR("failed to initialize ctrl, rc = %d\n", rc);
>>>>> dp->ctrl = NULL;
>>>>> - goto error_ctrl;
>>>>> + goto error_link;
>>>>> }
>>>>> dp->audio = msm_dp_audio_get(dp->msm_dp_display.pdev, dp-
>>>>> >catalog);
>>>>> @@ -791,13 +794,11 @@ static int msm_dp_init_sub_modules(struct
>>>>> msm_dp_display_private *dp)
>>>>> rc = PTR_ERR(dp->audio);
>>>>> pr_err("failed to initialize audio, rc = %d\n", rc);
>>>>> dp->audio = NULL;
>>>>> - goto error_ctrl;
>>>>> + goto error_link;
>>>>> }
>>>>> return rc;
>>>>> -error_ctrl:
>>>>> - msm_dp_panel_put(dp->panel);
>>>>> error_link:
>>>>> msm_dp_aux_put(dp->aux);
>>>>> error:
>>>>> diff --git a/drivers/gpu/drm/msm/dp/dp_panel.c b/drivers/gpu/drm/
>>>>> msm/dp/dp_panel.c
>>>>> index
>>>>> 4e8ab75c771b1e3a2d62f75e9993e1062118482b..d9041e235104a74b3cc50ff2e307eae0c4301ef3 100644
>>>>> --- a/drivers/gpu/drm/msm/dp/dp_panel.c
>>>>> +++ b/drivers/gpu/drm/msm/dp/dp_panel.c
>>>>> @@ -118,14 +118,13 @@ static u32
>>>>> msm_dp_panel_get_supported_bpp(struct msm_dp_panel *msm_dp_panel,
>>>>> return min_supported_bpp;
>>>>> }
>>>>> -int msm_dp_panel_read_sink_caps(struct msm_dp_panel *msm_dp_panel,
>>>>> - struct drm_connector *connector)
>>>>> +int msm_dp_panel_read_link_caps(struct msm_dp_panel *msm_dp_panel)
>>>>> {
>>>>> int rc, bw_code;
>>>>> int count;
>>>>> struct msm_dp_panel_private *panel;
>>>>> - if (!msm_dp_panel || !connector) {
>>>>> + if (!msm_dp_panel) {
>>>>> DRM_ERROR("invalid input\n");
>>>>> return -EINVAL;
>>>>> }
>>>>> @@ -160,26 +159,29 @@ int msm_dp_panel_read_sink_caps(struct
>>>>> msm_dp_panel *msm_dp_panel,
>>>>> rc = drm_dp_read_downstream_info(panel->aux, msm_dp_panel-
>>>>> >dpcd,
>>>>> msm_dp_panel->downstream_ports);
>>>>> - if (rc)
>>>>> - return rc;
>>>>> + return rc;
>>>>> +}
>>>>> - drm_edid_free(msm_dp_panel->drm_edid);
>>>>> +int msm_dp_panel_read_edid(struct msm_dp_panel *msm_dp_panel,
>>>>> struct drm_connector *connector)
>>>>> +{
>>>>> + struct msm_dp_panel_private *panel;
>>>>> + const struct drm_edid *drm_edid;
>>>>> +
>>>>> + panel = container_of(msm_dp_panel, struct
>>>>> msm_dp_panel_private, msm_dp_panel);
>>>>> - msm_dp_panel->drm_edid = drm_edid_read_ddc(connector, &panel-
>>>>> >aux->ddc);
>>>>> + drm_edid = drm_edid_read_ddc(connector, &panel->aux->ddc);
>>>>> - drm_edid_connector_update(connector, msm_dp_panel->drm_edid);
>>>>> + drm_edid_connector_update(connector, drm_edid);
>>>>> - if (!msm_dp_panel->drm_edid) {
>>>>> + if (!drm_edid) {
>>>>> DRM_ERROR("panel edid read failed\n");
>>>>> /* check edid read fail is due to unplug */
>>>>> if (!msm_dp_catalog_link_is_connected(panel->catalog)) {
>>>>> - rc = -ETIMEDOUT;
>>>>> - goto end;
>>>>> + return -ETIMEDOUT;
>>>>> }
>>>>> }
>>>>> -end:
>>>>> - return rc;
>>>>> + return 0;
>>>>> }
>>>>> u32 msm_dp_panel_get_mode_bpp(struct msm_dp_panel *msm_dp_panel,
>>>>> @@ -208,15 +210,20 @@ u32 msm_dp_panel_get_mode_bpp(struct
>>>>> msm_dp_panel *msm_dp_panel,
>>>>> int msm_dp_panel_get_modes(struct msm_dp_panel *msm_dp_panel,
>>>>> struct drm_connector *connector)
>>>>> {
>>>>> + struct msm_dp_panel_private *panel;
>>>>> + const struct drm_edid *drm_edid;
>>>>> +
>>>>> if (!msm_dp_panel) {
>>>>> DRM_ERROR("invalid input\n");
>>>>> return -EINVAL;
>>>>> }
>>>>> - if (msm_dp_panel->drm_edid)
>>>>> - return drm_edid_connector_add_modes(connector);
>>>>> + panel = container_of(msm_dp_panel, struct
>>>>> msm_dp_panel_private, msm_dp_panel);
>>>>> +
>>>>> + drm_edid = drm_edid_read_ddc(connector, &panel->aux->ddc);
>>>>> + drm_edid_connector_update(connector, drm_edid);
>>>>
>>>> If EDID has been read and processed after HPD high event, why do we
>>>> need
>>>> to re-read it again? Are we expecting that EDID will change?
>>>>
>>> Here we indeed don't need to read the EDID again, so we can directly
>>> call
>>> drm_edid_connector_add_modes. Thanks.
>>>>> - return 0;
>>>>> + return drm_edid_connector_add_modes(connector);
>>>>> }
>>>>> static u8 msm_dp_panel_get_edid_checksum(const struct edid *edid)
>>>>> @@ -229,6 +236,7 @@ static u8 msm_dp_panel_get_edid_checksum(const
>>>>> struct edid *edid)
>>>>> void msm_dp_panel_handle_sink_request(struct msm_dp_panel
>>>>> *msm_dp_panel)
>>>>> {
>>>>> struct msm_dp_panel_private *panel;
>>>>> + const struct drm_edid *drm_edid;
>>>>> if (!msm_dp_panel) {
>>>>> DRM_ERROR("invalid input\n");
>>>>> @@ -238,8 +246,13 @@ void msm_dp_panel_handle_sink_request(struct
>>>>> msm_dp_panel *msm_dp_panel)
>>>>> panel = container_of(msm_dp_panel, struct
>>>>> msm_dp_panel_private, msm_dp_panel);
>>>>> if (panel->link->sink_request & DP_TEST_LINK_EDID_READ) {
>>>>> + drm_edid = drm_edid_read_ddc(msm_dp_panel->connector,
>>>>> &panel->aux->ddc);
>>>>
>>>> And again....
>>>>
>>> Here we need the struct edid,since we drop the cached drm_edid, so we
>>> need
>>> to read it again. Or we can return the drm_edid from
>>> msm_dp_panel_read_edid
>>> and pass it to msm_dp_panel_handle_sink_request, then we don't need
>>> to read
>>> drm_edid here. Emm, I'm still a bit curious why we can't cache the
>>> drm_edid?
>>> It would help us to access it when needed. Emm, i see other drivers also
>>> cache it.
>>
>> Yes, they can cache EDID. However, in this case we don't even need it at
>> all. This piece needs to be rewritten to use
>> drm_dp_send_real_edid_checksum(), connector->real_edid_checksum.
>>
>> Corresponding changes can be submitted separately.
>>
> Got it, thanks, will separate this patch from MST patches.. Even if we
> use drm_dp_send_real_edid_checksum to send connector-
> >real_edid_checksum, that’s only when the EDID state is incorrect.
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/
> drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c?h=v6.16-rc3#n1020
> When the EDID is read correctly, it should send edid->checksum instead.
I wonder if we should fix the drm_edid to always set real_edid_checksum
instead.
>>
>
--
With best wishes
Dmitry
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