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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 We also eliminate dsi_phy_[enable|disable]_resource functions, which are superseded by runtime PM.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 <loic.poulain@oss.qualcomm.com> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com> Patchwork: https://patchwork.freedesktop.org/patch/663239/ Link: https://lore.kernel.org/r/20250709140836.124143-1-loic.poulain@oss.qualcomm.com Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com> |
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Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.