Re: [PATCH v1 0/3] clk: meson: small fixes for HDMI PLL OD

[Jerome Brunet <jbrunet@baylibre.com>]

On lun. 05 janv. 2026 at 21:47, Martin Blumenstingl <martin.blumenstingl@googlemail.com> wrote:

> Hi Jerome,
>
> this series contains two fixes for preventing HDMI PLL OD /8 on
> GXL/GXM and G12A/G12B/SM1, like the downstream driver does. See:
> - downstream GXBB code: [0]
> - downstream GXL/GXM code: [1]
> - downstream G12A/G12B/SM1 code: [2]
>
> I have verified this on GXL (Le Potato) by setting HDMI PLL OD1 to 0x3
> (which should result in divide-by-8). The resulting frequency reported
> by meson-clk-msr is double (meaning: only divide-by-4) compared to what
> CCF sees.
>
> These are not critical for now since the CCF code-path for the HDMI PLL
> is read-only (as drm/meson directly programs the registers).
>
> Additionally there's a cosmetic fix to use the HHI_HDMI_PLL_CNTL3 macro
> instead of calculating HHI_HDMI_PLL_CNTL + 8.
>
>
> [0] https://github.com/hardkernel/linux/blob/0e658067af67835a625e41e289effc4ee390d62f/drivers/amlogic/media/vout/hdmitx/hdmi_tx_20/hw/hw_clk.c#L505-L627
> [1] https://github.com/hardkernel/linux/blob/0e658067af67835a625e41e289effc4ee390d62f/drivers/amlogic/media/vout/hdmitx/hdmi_tx_20/hw/hw_gxl.c#L501-L553
> [2] https://github.com/hardkernel/linux/blob/0e658067af67835a625e41e289effc4ee390d62f/drivers/amlogic/media/vout/hdmitx/hdmi_tx_20/hw/hw_g12a.c#L671-L721
>
>
> Martin Blumenstingl (3):
>   clk: meson: gxbb: Limit the HDMI PLL OD to /4 on GXL/GXM SoCs
>   clk: meson: g12a: Limit the HDMI PLL OD to /4
>   clk: meson: gxbb: use the existing HHI_HDMI_PLL_CNTL3 macro

Looks good.

I'd like to add a comment like this in the code

+/*
+ * GXL hdmi OD dividers are POWER_OF_TWO dividers but limited to /4.
+ * A divider value of 3 should map to /8 but instead map /4 so ignore it.
+ */

(and a similar one for the G12). Is this Ok with you ?

>
>  drivers/clk/meson/g12a.c | 13 ++++++++++---
>  drivers/clk/meson/gxbb.c | 19 +++++++++++++------
>  2 files changed, 23 insertions(+), 9 deletions(-)

-- 
Jerome

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