linux-kernel - Re: [PATCH 2/3] pmdomain: imx8mp-blk-ctrl: imx8mp

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Date: Sat, 27 Jan 2024 12:19:50 -0600
From: Adam Ford <aford173@...il.com>
To: linux-pm@...r.kernel.org
Cc: Sandor Yu <Sandor.yu@....com>, Jacky Bai <ping.bai@....com>, 
	Rob Herring <robh+dt@...nel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Conor Dooley <conor+dt@...nel.org>, 
	Shawn Guo <shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>, 
	Pengutronix Kernel Team <kernel@...gutronix.de>, Fabio Estevam <festevam@...il.com>, 
	NXP Linux Team <linux-imx@....com>, Ulf Hansson <ulf.hansson@...aro.org>, 
	Lucas Stach <l.stach@...gutronix.de>, devicetree@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	Marek Vasut <marex@...x.de>, "Peng Fan (OSS)" <peng.fan@....nxp.com>
Subject: Re: [PATCH 2/3] pmdomain: imx8mp-blk-ctrl: imx8mp_blk: Add fdcc clock
 to hdmimix domain

On Sat, Jan 6, 2024 at 4:40 PM Adam Ford <aford173@...il.com> wrote:
>
> According to i.MX8MP RM and HDMI ADD, the fdcc clock is part of
> hdmi rx verification IP that should not enable for HDMI TX.
> But actually if the clock is disabled before HDMI/LCDIF probe,
> LCDIF will not get pixel clock from HDMI PHY and print the error
> logs:
>
> [CRTC:39:crtc-2] vblank wait timed out
> WARNING: CPU: 2 PID: 9 at drivers/gpu/drm/drm_atomic_helper.c:1634 drm_atomic_helper_wait_for_vblanks.part.0+0x23c/0x260
>
> Add fdcc clock to LCDIF and HDMI TX power domains to fix the issue.

Peng (or anyone from NXP),

I borrowed this patch from the NXP down-stream kernel for two reasons:
 It's in NXP's branch to address an error & move the fdcc clock out of
the HDMI-tx driver due to questions/feedback that Lucas got on that
driver.

The FDCC clock isn't well documented, and it seems like it's necessary
for the HDMI-TX, but I'd like to make sure this is the proper
solution, and I haven't received any additional feedback.
Can someone from NXP confirm that really is the proper solution?

thank you,

adam

>
> Signed-off-by: Sandor Yu <Sandor.yu@....com>
> Reviewed-by: Jacky Bai <ping.bai@....com>
> Signed-off-by: Adam Ford <aford173@...il.com>
> ---
> The original work was from Sandor on the NXP Down-stream kernel
>
> diff --git a/drivers/pmdomain/imx/imx8mp-blk-ctrl.c b/drivers/pmdomain/imx/imx8mp-blk-ctrl.c
> index e3203eb6a022..a56f7f92d091 100644
> --- a/drivers/pmdomain/imx/imx8mp-blk-ctrl.c
> +++ b/drivers/pmdomain/imx/imx8mp-blk-ctrl.c
> @@ -55,7 +55,7 @@ struct imx8mp_blk_ctrl_domain_data {
>         const char *gpc_name;
>  };
>
> -#define DOMAIN_MAX_CLKS 2
> +#define DOMAIN_MAX_CLKS 3
>  #define DOMAIN_MAX_PATHS 3
>
>  struct imx8mp_blk_ctrl_domain {
> @@ -457,8 +457,8 @@ static const struct imx8mp_blk_ctrl_domain_data imx8mp_hdmi_domain_data[] = {
>         },
>         [IMX8MP_HDMIBLK_PD_LCDIF] = {
>                 .name = "hdmiblk-lcdif",
> -               .clk_names = (const char *[]){ "axi", "apb" },
> -               .num_clks = 2,
> +               .clk_names = (const char *[]){ "axi", "apb", "fdcc" },
> +               .num_clks = 3,
>                 .gpc_name = "lcdif",
>                 .path_names = (const char *[]){"lcdif-hdmi"},
>                 .num_paths = 1,
> @@ -483,8 +483,8 @@ static const struct imx8mp_blk_ctrl_domain_data imx8mp_hdmi_domain_data[] = {
>         },
>         [IMX8MP_HDMIBLK_PD_HDMI_TX] = {
>                 .name = "hdmiblk-hdmi-tx",
> -               .clk_names = (const char *[]){ "apb", "ref_266m" },
> -               .num_clks = 2,
> +               .clk_names = (const char *[]){ "apb", "ref_266m", "fdcc" },
> +               .num_clks = 3,
>                 .gpc_name = "hdmi-tx",
>         },
>         [IMX8MP_HDMIBLK_PD_HDMI_TX_PHY] = {
> --
> 2.43.0
>