linux-kernel - Re: [RFC 0/3] clk: imx: Implement blk-ctl driver for i.MX8MN

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Date:   Mon, 26 Oct 2020 16:55:16 +0200
From:   Abel Vesa <abel.vesa@....com>
To:     Adam Ford <aford173@...il.com>
Cc:     Marek Vasut <marex@...x.de>, linux-clk <linux-clk@...r.kernel.org>,
        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>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        arm-soc <linux-arm-kernel@...ts.infradead.org>,
        devicetree <devicetree@...r.kernel.org>
Subject: Re: [RFC 0/3] clk: imx: Implement blk-ctl driver for i.MX8MN

On 20-10-25 11:05:32, Adam Ford wrote:
> On Sun, Oct 25, 2020 at 7:19 AM Marek Vasut <marex@...x.de> wrote:
> >
> > On 10/25/20 1:05 PM, Abel Vesa wrote:
> >
> > [...]
> >
> > >> Together, both the GPC and the clk-blk driver should be able to pull
> > >> the multimedia block out of reset.  Currently, the GPC can handle the
> > >> USB OTG and the GPU, but the LCDIF and MIPI DSI appear to be gated by
> > >> the clock block
> > >>
> > >> My original patch RFC didn't include the imx8mn node, because it
> > >> hangs, but the node I added looks like:
> > >>
> > >> media_blk_ctl: clock-controller@...28000 {
> > >>      compatible = "fsl,imx8mn-media-blk-ctl", "syscon";
> > >>      reg = <0x32e28000 0x1000>;
> > >>      #clock-cells = <1>;
> > >>      #reset-cells = <1>;
> > >> };
> > >>
> > >> I was hoping you might have some feedback on the 8mn clk-blk driver
> > >> since you did the 8mp clk-blk drive and they appear to be very
> > >> similar.
> > >>
> > >
> > > I'll do you one better still. I'll apply the patch in my tree and give it
> > > a test tomorrow morning.
> 
> I do have some more updates on how to get the system to not hang, and
> to enumerate more clocks.
> Looking at Marek's work on enabling clocks in the 8MM, he added a
> power-domain in dispmix_blk_ctl pointing to the dispmix in the GPC.
> By forcing the GPC driver to write 0x1fff  to 32e28004, 0x7f to
> 32e28000 and 0x30000 to 32e28008, the i.MX8MM can bring the display
> clocks out of reset.
> 

Yeah, that makes sense. Basically, it was trying to disable unused clocks
(see clk_disable_unused) but in order to disable the clocks from the
media BLK_CTL (which I think should be renamed in display BLK_CTL) the
PD need to be on. Since you initially didn't give it any PD, it was trying
to blindly write/read the gate bit and therefore freeze.

> Unfortunately, the i.MX8MN needs to have 0x100 written to both
> 32e28000 and 32e28004, and the values written for the 8MM are not
> compatible.
> By forcing the GPC to write those values, I can get  lcdif_pixel_clk
> and the mipi_dsi_clkref  appearing on the Nano.

I'm trying to make a branch with all the patches for all i.MX8M so I
can keep track of it all. On this branch I've also applied the 
following patchset from Lucas Stach:
https://www.spinics.net/lists/arm-kernel/msg843007.html
but I'm getting the folowing errors:

[   16.690885] imx-pgc imx-pgc-domain.3: failed to power up ADB400
[   16.716839] imx-pgc imx-pgc-domain.3: failed to power up ADB400
[   16.730500] imx-pgc imx-pgc-domain.3: failed to power up ADB400

Lucas, any thoughts?

Maybe it's something related to 8MN.

Will dig further, see what pops out.

> 
>  video_pll1_ref_sel                0        0        0    24000000
>      0     0  50000
>        video_pll1                     0        0        0   594000000
>         0     0  50000
>           video_pll1_bypass           0        0        0   594000000
>         0     0  50000
>              video_pll1_out           0        0        0   594000000
>         0     0  50000
>                 disp_pixel            0        0        0   594000000
>         0     0  50000
>                    lcdif_pixel_clk       0        0        0
> 594000000          0     0  50000
>                    disp_pixel_clk       0        0        0
> 594000000          0     0  50000
>                 dsi_phy_ref           0        0        0    27000000
>         0     0  50000
>                    mipi_dsi_clkref       0        0        0
> 27000000          0     0  50000
> 
> I am not 100% certain the clock parents  in the clk block driver for
> the 8MN are correct, and I am not seeing the mipi_dsi_pclk
> 
> Once the dust settles on the GPC decision for Mini and Nano, I think
> we'll need a more generic way to pass the bits we need to set in clock
> block to the GPC.
> 
> adam
> >
> > You can also apply the one for 8MM:
> > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Flinux-arm-kernel%2F20201003224555.163780-5-marex%40denx.de%2F&amp;data=04%7C01%7Cabel.vesa%40nxp.com%7Cae966cce11204214fb1908d878ffd492%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C637392387462398200%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=M944BaOI7Sa1RmI0nwrshKaM7MGMEN5pWgjmYqXZkns%3D&amp;reserved=0