linux-kernel - Re: [PATCH V2 0/4] clk: imx: Improve imx8mm/imx8mn LCDIF clocks

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Date:   Thu, 23 Mar 2023 17:44:33 -0500
From:   Adam Ford <aford173@...il.com>
To:     Fabio Estevam <festevam@...il.com>
Cc:     linux-clk@...r.kernel.org, aford@...conembedded.com,
        Abel Vesa <abelvesa@...nel.org>, Peng Fan <peng.fan@....com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        NXP Linux Team <linux-imx@....com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2 0/4] clk: imx: Improve imx8mm/imx8mn LCDIF clocks

On Thu, Mar 23, 2023 at 5:31 PM Fabio Estevam <festevam@...il.com> wrote:
>
> On Mon, Mar 20, 2023 at 11:31 PM Adam Ford <aford173@...il.com> wrote:
> >
> > Both the i.MX8M Mini and Nano have a video_pll which can be used
> > to source a clock which feeds the lcdif interface.  This interface
> > currently fixes video_pll and divides down the clock feeding LCDIF.
> > However, when connected to an HDMI bridge chip that supports a
> > variety of video resolutions and refresh rates, the only settings
> > that properly sync are ones that evenly divide from the video_pll_out
> > clock.
> >
> > This series adds the ability for the clk-compolsite-8m to
> > request a better parent clock rate if the proper clock flag is
> > enable and sets that flag in the corresponding imx8mm and
> > imx8mn video_pll clocks to increase the number of resolutions
> > and refresh rates timings that the LCDIF can produce.
> >
> > This also has a side benefit of allowing the video-pll to run
> > at a lower clock speed which can potentially save some power
> > depending on the requested resolution and refresh rate.
> >
> > V2:  Split off the new imx8m_clk_hw_composite_flags definition
> >      into its own patch and re-order to fix build error.
> >
> > Adam Ford (3):
> >   clk: imx: composite-8m: Add support to determine_rate
> >   clk: imx8mm: Let IMX8MM_CLK_LCDIF_PIXEL set parent rate
> >   clk: imx: Let IMX8MN_CLK_DISP_PIXEL set parent rate
>
> For the series:
>
> Reviewed-by: Fabio Estevam <festevam@...il.com>
>
Thanks!

> Should drivers/clk/imx/clk-imx8mp.c also be adjusted in the same way?

The LVDS and the DSI clocks are shared from a common parent, so I am
not sure of the impact of this.  I have an IMX8MP and I have it
working with DSI->HDMI and the LVDS, but I was waiting on the DSI
series from Jagan to get applied first and I wanted to make sure this
series gets accepted before I started work on the 8MP.

I will be traveling to Thailand for the next 3 weeks, so I'm hoping to
review the 8MP when I return.

adam