drm/msm/dsi: Fix 14nm DSI PHY PLL Lock issue

To configure and enable the DSI PHY PLL clocks, the MDSS AHB clock must
be active for MMIO operations. Typically, this AHB clock is enabled as
part of the DSI PHY interface enabling (dsi_phy_enable_resource).

However, since these PLL clocks are registered as clock entities, they
can be enabled independently of the DSI PHY interface, leading to
enabling failures and subsequent warnings:

```
msm_dsi_phy 5e94400.phy: [drm:dsi_pll_14nm_vco_prepare] *ERROR* DSI PLL lock failed
------------[ cut here ]------------
dsi0pllbyte already disabled
WARNING: CPU: 3 PID: 1 at drivers/clk/clk.c:1194 clk_core_disable+0xa4/0xac
CPU: 3 UID: 0 PID: 1 Comm: swapper/0 Tainted:
Tainted: [W]=WARN
Hardware name: Qualcomm Technologies, Inc. Robotics RB1 (DT)
pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[...]
```

This issue is particularly prevalent at boot time during the disabling of
unused clocks (clk_disable_unused()) which includes enabling the parent
clock(s) when CLK_OPS_PARENT_ENABLE flag is set (this is the case for the
14nm DSI PHY PLL consumers).

To resolve this issue, we move the AHB clock as a PM dependency of the DSI
PHY device (via pm_clk). Since the DSI PHY device is the parent of the PLL
clocks, this resolves the PLL/AHB dependency. Now the AHB clock is enabled
prior the PLL clk_prepare callback, as part of the runtime-resume chain.

We also eliminate dsi_phy_[enable|disable]_resource functions, which are
superseded by runtime PM.

Note that it breaks compatibility with kernels before 6.0, as we do not
support anymore the legacy `iface_clk` name.

Signed-off-by: Loic Poulain <[email protected]>
Reviewed-by: Dmitry Baryshkov <[email protected]>
Patchwork: https://patchwork.freedesktop.org/patch/663239/
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Dmitry Baryshkov <[email protected]>

1 files changed, 0 insertions, 1 deletions

diff --git a/drivers/gpu/drm/msm/dsi/phy/dsi_phy.h b/drivers/gpu/drm/msm/dsi/phy/dsi_phy.h
index c558f8df1684..3cbf08231492 100644
--- a/drivers/gpu/drm/msm/dsi/phy/dsi_phy.h
+++ b/drivers/gpu/drm/msm/dsi/phy/dsi_phy.h
@@ -104,7 +104,6 @@ struct msm_dsi_phy {
 	phys_addr_t lane_size;
 	int id;
 
-	struct clk *ahb_clk;
 	struct regulator_bulk_data *supplies;
 
 	struct msm_dsi_dphy_timing timing;