Re: [PATCH v2 3/7] clk: renesas: r8a779g0: Add display related clocks

From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Tomi Valkeinen <tomi.valkeinen+renesas@ideasonboard.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>,
	Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Magnus Damm <magnus.damm@gmail.com>,
	dri-devel@lists.freedesktop.org,
	linux-renesas-soc@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Andrzej Hajda <andrzej.hajda@intel.com>,
	Neil Armstrong <neil.armstrong@linaro.org>,
	Robert Foss <robert.foss@linaro.org>,
	Jonas Karlman <jonas@kwiboo.se>,
	Jernej Skrabec <jernej.skrabec@gmail.com>
Subject: Re: [PATCH v2 3/7] clk: renesas: r8a779g0: Add display related clocks
Date: Wed, 30 Nov 2022 20:18:11 +0100	[thread overview]
Message-ID: <CAMuHMdUjCS6q44XmTanu=R68GyuVECLa0B-1AFg1CUD_oV4DuA@mail.gmail.com> (raw)
In-Reply-To: <20221123065946.40415-4-tomi.valkeinen+renesas@ideasonboard.com>

Hi Tomi,

On Wed, Nov 23, 2022 at 8:00 AM Tomi Valkeinen
<tomi.valkeinen+renesas@ideasonboard.com> wrote:
> Add clocks related to display which are needed to get the DSI output
> working.
>
> Extracted from Renesas BSP tree.
>
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen+renesas@ideasonboard.com>
> Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

Thanks for your patch!

> --- a/drivers/clk/renesas/r8a779g0-cpg-mssr.c
> +++ b/drivers/clk/renesas/r8a779g0-cpg-mssr.c
> @@ -145,6 +145,8 @@ static const struct cpg_core_clk r8a779g0_core_clks[] __initconst = {
>         DEF_FIXED("viobusd2",   R8A779G0_CLK_VIOBUSD2,  CLK_VIO,        2, 1),
>         DEF_FIXED("vcbus",      R8A779G0_CLK_VCBUS,     CLK_VC,         1, 1),
>         DEF_FIXED("vcbusd2",    R8A779G0_CLK_VCBUSD2,   CLK_VC,         2, 1),
> +       DEF_FIXED("dsiref",     R8A779G0_CLK_DSIREF,    CLK_PLL5_DIV4,  48, 1),
> +       DEF_DIV6P1("dsiext",    R8A779G0_CLK_DSIEXT,    CLK_PLL5_DIV4,  0x884),
>
>         DEF_GEN4_SDH("sd0h",    R8A779G0_CLK_SD0H,      CLK_SDSRC,         0x870),
>         DEF_GEN4_SD("sd0",      R8A779G0_CLK_SD0,       R8A779G0_CLK_SD0H, 0x870),
> @@ -161,6 +163,14 @@ static const struct mssr_mod_clk r8a779g0_mod_clks[] __initconst = {
>         DEF_MOD("avb0",         211,    R8A779G0_CLK_S0D4_HSC),
>         DEF_MOD("avb1",         212,    R8A779G0_CLK_S0D4_HSC),
>         DEF_MOD("avb2",         213,    R8A779G0_CLK_S0D4_HSC),
> +

Weird horizontal and vertical spacing below...

> +       DEF_MOD("dis0",                 411,    R8A779G0_CLK_S0D3),

I doubt this parent clock is correct.
Based on Table 8.1.4e ("Lists of CPG clocks generated from PLL5"),
this should be one of the VIOBUS clocks.
VIOBUSD2 has the same rate as S0D3, so I'd use that one.

> +       DEF_MOD("dsitxlink0",           415,    R8A779G0_CLK_DSIREF),
> +       DEF_MOD("dsitxlink1",           416,    R8A779G0_CLK_DSIREF),
> +
> +       DEF_MOD("fcpvd0",               508,    R8A779G0_CLK_S0D3),
> +       DEF_MOD("fcpvd1",               509,    R8A779G0_CLK_S0D3),

Likewise.

> +
>         DEF_MOD("hscif0",       514,    R8A779G0_CLK_SASYNCPERD1),
>         DEF_MOD("hscif1",       515,    R8A779G0_CLK_SASYNCPERD1),
>         DEF_MOD("hscif2",       516,    R8A779G0_CLK_SASYNCPERD1),
> @@ -193,6 +203,10 @@ static const struct mssr_mod_clk r8a779g0_mod_clks[] __initconst = {
>         DEF_MOD("tmu3",         716,    R8A779G0_CLK_SASYNCPERD2),
>         DEF_MOD("tmu4",         717,    R8A779G0_CLK_SASYNCPERD2),
>         DEF_MOD("tpu0",         718,    R8A779G0_CLK_SASYNCPERD4),
> +
> +       DEF_MOD("vspd0",                830,    R8A779G0_CLK_S0D1_VIO),
> +       DEF_MOD("vspd1",                831,    R8A779G0_CLK_S0D1_VIO),

While S0D1_VIO is a VIO clock, it is clocked from PLL1, which supports
spread-spectrum, unlike PLL5.
Again, based on Table 8.1.4e ("Lists of CPG clocks generated from
PLL5"), this should be one of the VIOBUS clocks.

Not that all of this matters a lot: all of these parents are always-on,
and I think "dis0" is the only clock where we care about the actual
clock rate?

> +
>         DEF_MOD("wdt1:wdt0",    907,    R8A779G0_CLK_R),
>         DEF_MOD("cmt0",         910,    R8A779G0_CLK_R),
>         DEF_MOD("cmt1",         911,    R8A779G0_CLK_R),

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds