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SubjectRe: [PATCH] drm/bridge: parade-ps8640: Link device to ensure suspend/resume order
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Il 04/01/22 15:22, Robert Foss ha scritto:
> Hey AngeloGioacchino,
>
> On Tue, 2 Nov 2021 at 14:08, AngeloGioacchino Del Regno
> <angelogioacchino.delregno@collabora.com> wrote:
>>
>> Entering suspend while the display attached to this bridge is still on
>> makes the resume sequence to resume the bridge first, display last:
>> when this happens, we get a timeout while resuming the bridge, as its
>> MCU will get stuck due to the display being unpowered.
>>
>> On the other hand, on mt8173-elm, closing the lid makes the display to
>> get powered off first, bridge last, so at resume time the sequence is
>> swapped (compared to the first example) and everything just works
>> as expected.
>>
>> Add a stateless device link to the DRM device that this bridge belongs
>> to, ensuring a correct resume sequence and solving the unability to
>> correctly resume bridge operation in the first mentioned example.
>>
>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
>> ---
>> drivers/gpu/drm/bridge/parade-ps8640.c | 22 ++++++++++++++++++++--
>> 1 file changed, 20 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/bridge/parade-ps8640.c b/drivers/gpu/drm/bridge/parade-ps8640.c
>> index 45100edd745b..191cc196c9d1 100644
>> --- a/drivers/gpu/drm/bridge/parade-ps8640.c
>> +++ b/drivers/gpu/drm/bridge/parade-ps8640.c
>> @@ -100,6 +100,7 @@ struct ps8640 {
>> struct regulator_bulk_data supplies[2];
>> struct gpio_desc *gpio_reset;
>> struct gpio_desc *gpio_powerdown;
>> + struct device_link *link;
>> bool powered;
>> };
>>
>> @@ -460,10 +461,23 @@ static int ps8640_bridge_attach(struct drm_bridge *bridge,
>> goto err_aux_register;
>> }
>>
>> + ps_bridge->link = device_link_add(bridge->dev->dev, dev, DL_FLAG_STATELESS);
>> + if (!ps_bridge->link) {
>> + dev_err(dev, "failed to create device link");
>> + ret = -EINVAL;
>> + goto err_devlink;
>> + }
>> +
>> /* Attach the panel-bridge to the dsi bridge */
>> - return drm_bridge_attach(bridge->encoder, ps_bridge->panel_bridge,
>> + ret = drm_bridge_attach(bridge->encoder, ps_bridge->panel_bridge,
>> &ps_bridge->bridge, flags);
>> + if (ret)
>> + goto err_bridge_attach;
>>
>> +err_bridge_attach:
>> + device_link_del(ps_bridge->link);
>> +err_devlink:
>> + drm_dp_aux_unregister(&ps_bridge->aux);
>> err_aux_register:
>> mipi_dsi_detach(dsi);
>> err_dsi_attach:
>> @@ -473,7 +487,11 @@ static int ps8640_bridge_attach(struct drm_bridge *bridge,
>>
>> static void ps8640_bridge_detach(struct drm_bridge *bridge)
>> {
>> - drm_dp_aux_unregister(&bridge_to_ps8640(bridge)->aux);
>> + struct ps8640 *ps_bridge = bridge_to_ps8640(bridge);
>> +
>> + drm_dp_aux_unregister(&ps_bridge->aux);
>> + if (ps_bridge->link)
>> + device_link_del(ps_bridge->link);
>> }
>>
>> static struct edid *ps8640_bridge_get_edid(struct drm_bridge *bridge,
>> --
>> 2.33.1
>>
>
> This patch does not apply on drm-misc-next, could you rebase it on the
> current branch?
>

Sure, I'll rebase it asap.

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