[PATCH v6 03/12] drm/bridge: cdns-dsi: Fix phy de-init and flag it so

[Aradhya Bhatia]

From: Aradhya Bhatia <a-bhat...@ti.com>

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.

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-bhat...@ti.com>
Signed-off-by: Aradhya Bhatia <aradhya.bha...@linux.dev>
---
 drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c 
b/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
index 056583e81155..47550891427c 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
@@ -672,6 +672,10 @@ static void cdns_dsi_bridge_disable(struct drm_bridge 
*bridge)
        if (dsi->platform_ops && dsi->platform_ops->disable)
                dsi->platform_ops->disable(dsi);
 
+       phy_power_off(dsi->dphy);
+       dsi->link_initialized = false;
+       dsi->phy_initialized = false;
+
        pm_runtime_put(dsi->base.dev);
 }
 
@@ -698,7 +702,6 @@ static void cdns_dsi_hs_init(struct cdns_dsi *dsi)
               DPHY_CMN_PDN | DPHY_PLL_PDN,
               dsi->regs + MCTL_DPHY_CFG0);
 
-       phy_init(dsi->dphy);
        phy_set_mode(dsi->dphy, PHY_MODE_MIPI_DPHY);
        phy_configure(dsi->dphy, &output->phy_opts);
        phy_power_on(dsi->dphy);
@@ -1120,6 +1123,8 @@ static int __maybe_unused cdns_dsi_resume(struct device 
*dev)
        clk_prepare_enable(dsi->dsi_p_clk);
        clk_prepare_enable(dsi->dsi_sys_clk);
 
+       phy_init(dsi->dphy);
+
        return 0;
 }
 
@@ -1127,10 +1132,11 @@ static int __maybe_unused cdns_dsi_suspend(struct 
device *dev)
 {
        struct cdns_dsi *dsi = dev_get_drvdata(dev);
 
+       phy_exit(dsi->dphy);
+
        clk_disable_unprepare(dsi->dsi_sys_clk);
        clk_disable_unprepare(dsi->dsi_p_clk);
        reset_control_assert(dsi->dsi_p_rst);
-       dsi->link_initialized = false;
        return 0;
 }
 
-- 
2.34.1