Re: [PATCH v7 1/5] clk: bcm: rpi: Manage clock rate in prepare/unprepare callbacks

[Mark Brown <broonie@kernel.org>]

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On Tue, Mar 31, 2026 at 11:32:07AM -0300, Maíra Canal wrote:
> On 31/03/26 09:49, Mark Brown wrote:
> > On Thu, Mar 12, 2026 at 06:34:23PM -0300, Maíra Canal wrote:

> > > Rather than pushing rate management to clock consumers, handle it
> > > directly in the clock framework's prepare/unprepare callbacks. In
> > > unprepare, set the rate to the minimum before disabling the clock.
> > > In prepare, for clocks marked with `maximize` (currently v3d),
> > > restore the rate to the maximum after enabling.

> > I'm seeing boot regressions in -next with NFS root on Raspberry Pi 3B+
> > which bisect to this commit.  We get a likely unrelated oops from the
> > firmware interface and the boot grinds to a halt some time later since
> > the ethernet never comes up:

> I've managed to address this issue locally with the following diff:

> diff --git a/drivers/clk/bcm/clk-raspberrypi.c
> b/drivers/clk/bcm/clk-raspberrypi.c
> index df2d246eb6ef..ef5ae3b4adca 100644
> --- a/drivers/clk/bcm/clk-raspberrypi.c
> +++ b/drivers/clk/bcm/clk-raspberrypi.c
> @@ -160,6 +160,7 @@ raspberrypi_clk_variants[RPI_FIRMWARE_NUM_CLK_ID] = {
>         [RPI_FIRMWARE_VEC_CLK_ID] = {
>                 .export = true,
>                 .minimize = true,
> +               .flags = CLK_IGNORE_UNUSED,
>         },
>         [RPI_FIRMWARE_DISP_CLK_ID] = {
>                 .export = true,

> It looks like the VEC_CLK can't be disabled at boot time. Otherwise, a
> bus lookup will happen (similar what happens to other RPi firmware
> clocks).

> Is it possible for me to test this change in LAVA CI before sending it
> to the list? Just to double check that this patch indeed fixes the
> issue on your side as well.

I can give you access to submit jobs easily enough, if you're already
familiar with LAVA and have somewhere to host the binaries that'd work.
It might be more straightforward for me to just test it.

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