Re: [PATCH] clk: qcom: mmcc-sdm660: enable the parent when pclk0_clk_src changes rate

[Dmitry Baryshkov]

On Fri, Oct 02, 2026 at 10:55:35AM -0300, Fabricio Akio via B4 Relay wrote:
> From: Fabricio Akio <fabricioakio@xxxxxxxxx>
> 
> pclk0_clk_src is fed by the DSI PHY PLL, which
> dsi_pll_14nm_vco_set_rate() resets and only clk_prepare() restarts. The
> DSI host sets the link rates before it prepares the PLL, so the RCG is
> updated against a stopped source, and if it is enabled at that point
> the update times out:
> 
>   pclk0_clk_src: rcg didn't update its configuration.
> 
> Seen on a board whose simple-framebuffer node lists the pixel clock:
> the RCG then reads enabled at msm's first modeset.
> 
> Set CLK_OPS_PARENT_ENABLE so the core prepares the PLL around the rate
> change, as dispcc-sm8250 does for its pixel clock sources since
> commit acf7a91d0b0e ("clk: qcom: dispcc-sm8250: Enable parents for pixel
> clocks").
> 
> Fixes: 5db3ae8b33de ("clk: qcom: Add SDM660 Multimedia Clock Controller (MMCC) driver")
> Signed-off-by: Fabricio Akio <fabricioakio@xxxxxxxxx>
> ---
> Tested on the Motorola Moto X4 (SDM630, payton) with the sdm660-mainline
> 7.2.y tree, sdm660_defconfig, DRM_MSM=m: without the flag the warning
> fires in most boots, with it never. At the stall the RCG reads root-on
> and the PLL stopped. With the display built in, clk_disable_unused()
> also prepares the PLL under this flag, and some boots then log "DSI PLL
> lock failed".
> ---
>  drivers/clk/qcom/mmcc-sdm660.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/clk/qcom/mmcc-sdm660.c b/drivers/clk/qcom/mmcc-sdm660.c
> index 9f8b8e29fa0f..bc95d0de75a3 100644
> --- a/drivers/clk/qcom/mmcc-sdm660.c
> +++ b/drivers/clk/qcom/mmcc-sdm660.c
> @@ -984,7 +984,8 @@ static struct clk_rcg2 pclk0_clk_src = {
>  		.parent_data = mmcc_xo_dsi0pll_dsi1pll,
>  		.num_parents = ARRAY_SIZE(mmcc_xo_dsi0pll_dsi1pll),
>  		.ops = &clk_pixel_ops,
> -		.flags = CLK_SET_RATE_PARENT | CLK_GET_RATE_NOCACHE,
> +		.flags = CLK_SET_RATE_PARENT | CLK_GET_RATE_NOCACHE |
> +			 CLK_OPS_PARENT_ENABLE,

The same fix must be applied to PCLK1 too.

>  	},
>  };
>  
> 
> ---
> base-commit: 9f24d789f03b22941b905ded43cb5ff8eea9ce62
> change-id: 20261002-sdm660-pclk0-parent-enable-8123c9ac71d8
> 
> Best regards,
> --  
> Fabricio Akio <fabricioakio@xxxxxxxxx>
> 
> 

-- 
With best wishes
Dmitry