[PATCH v2 01/38] drm/msm/dp: split msm_dp_panel_read_sink_caps() into two parts and drop panel drm_edid
Yongxing Mou
quic_yongmou at quicinc.com
Wed Aug 6 09:03:57 UTC 2025
On 2025/6/27 20:40, Dmitry Baryshkov wrote:
> 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.
>
Emm, can i understand that is another issue exist in the currently DRM..
>>>
>>
>
>
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