Re: [PATCH v4 03/11] drm/bridge: cdns-dsi: Fix Phy _init() and _exit()

From: Tomi Valkeinen
Date: Wed Jun 26 2024 - 06:25:29 EST


Hi,

On 22/06/2024 14:09, Aradhya Bhatia wrote:
Initialize the Phy during the cdns-dsi _resume(), and de-initialize it
during the _suspend().

Also power-off the Phy from bridge_disable.

Fixes: fced5a364dee ("drm/bridge: cdns: Convert to phy framework")
Signed-off-by: Aradhya Bhatia <a-bhatia1@xxxxxx>
---
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 5159c3f0853e..d89c32bae2b9 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;
}

So with this patch, phy_init/exit will be called in the resume/suspend functions. That looks fine.

But the phy_power_on/phy_power_off looks odd to me. Here you add phy_power_off() to cdns_dsi_bridge_disable(), which sounds fine. But phy_power_on() is called in cdns_dsi_hs_init(), and that is called in cdns_dsi_bridge_enable() (which sounds fine), but also in cdns_dsi_bridge_pre_enable().

So doesn't that mean cdns_dsi_hs_init() call in cdns_dsi_bridge_enable() is extra, as it effectively does nothing (it exists right away if dsi->phy_initialized == true)?

Tomi