On Sun, Jan 12, 2025 at 12:57:29AM +0530, Aradhya Bhatia wrote:
> From: Aradhya Bhatia <a-bhatia1@xxxxxx>
>
> The driver code doesn't have a de-initialization path as yet, and so it
> does not clear the phy_initialized flag while suspending. This is a
> problem because after resume the driver looks at this flag to determine
> if a Phy re-initialization is required or not. It is in fact required
> because the hardware is resuming from a suspend, but the driver does not
> carry out any re-initialization causing the D-Phy to not work at all.
>
> Add the counterpart of phy_power_on(), that is phy_power_off() from the
> _bridge_disable() and clear the flags so that the Phy can be initialized
> again when required.
>
> Move the Phy initialization from _bridge_enable() to _resume(), and
> de-initialize during the _suspend() - so that the phy_{init, exit}()
> take place once every resume/suspend cycle.
Is it okay to call phy_init() before writing MCTL_DPHY_CFG0 ?
>
> The order of calls still remains the same. phy_init() needs to be called
> before phy_power_on() - which happens still. What this patch changes is
> the frequency of the phy_init() call. Instead of it being called once
> every bridge enable/disable cycle, it is now being called once every
> resume/suspend cycle. This move has been considered safe after numerous
> tests with the hardware.
>
> Fixes: fced5a364dee ("drm/bridge: cdns: Convert to phy framework")
> Signed-off-by: Aradhya Bhatia <a-bhatia1@xxxxxx>
> Signed-off-by: Aradhya Bhatia <aradhya.bhatia@xxxxxxxxx>
> ---
> drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
--
With best wishes
Dmitry
