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

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Date: Mon, 29 Jan 2024 01:38:59 +0000
From: Sandor Yu <sandor.yu@....com>
To: Adam Ford <aford173@...il.com>, "linux-pm@...r.kernel.org"
	<linux-pm@...r.kernel.org>
CC: 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>, dl-linux-imx <linux-imx@....com>, Ulf
 Hansson <ulf.hansson@...aro.org>, Lucas Stach <l.stach@...gutronix.de>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, Marek Vasut <marex@...x.de>, "Peng Fan (OSS)"
	<peng.fan@....nxp.com>
Subject: RE: [EXT] Re: [PATCH 2/3] pmdomain: imx8mp-blk-ctrl: imx8mp_blk: Add
 fdcc clock to hdmimix domain



> -----Original Message-----
> From: Adam Ford <aford173@...il.com>
> Sent: 2024年1月28日 2:20
> 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>;
> dl-linux-imx <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: [EXT] Re: [PATCH 2/3] pmdomain: imx8mp-blk-ctrl: imx8mp_blk: Add
> fdcc clock to hdmimix domain
> 
> Caution: This is an external email. Please take care when clicking links or
> opening attachments. When in doubt, report the message using the 'Report
> this email' button
> 
> 
> 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

Hi Adam,

In NXP internal document, the clock HDMI_FDCC_TST_CLK_ROOT was for internal use only for future NXP development IP.
It should not be exposed to customer in document but unfortunately it have to be enabled for HDMITX.

I submitted a request ticket to the design team several months ago, 
Generally, tickets of this didn't get the priority in design team and I haven’t received any valuable feedback.
Once design team confirmed, I think the document will update to add the fdcc clock.

B.R
Sandor

> 
> >
> > 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
> >