linux-kernel - Re: [PATCH 1/1] clk: composite: Fix 'switching' to same clock

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Date:   Wed, 3 Nov 2021 22:13:28 +0100
From:   Martin Blumenstingl <martin.blumenstingl@...glemail.com>
To:     Alexander Stein <alexander.stein@...tq-group.com>
Cc:     Michael Turquette <mturquette@...libre.com>,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        Alex Bee <knaerzche@...il.com>, Chen-Yu Tsai <wens@...e.org>
Subject: Re: [PATCH 1/1] clk: composite: Fix 'switching' to same clock

Hi Alexander,

On Wed, Nov 3, 2021 at 1:24 PM Alexander Stein
<alexander.stein@...tq-group.com> wrote:
>
> During commit 6594988fd625 ("clk: composite: Use rate_ops.determine_rate
> when also a mux is available") setting req->best_parent_hw got lost,
> so best_parent_hw stays NULL during switch to the same parent. This
> results in the (debug) message:
>   clk_calc_new_rates: lcdif_pixel not gated but wants to reparent
> and the following rate change is dropped.
Thanks for investigating and fixing this!

note to myself: only clocks with CLK_SET_RATE_NO_REPARENT are affected.
This might be the reason why it wasn't spotted on Rockchip SoCs (yet).
I have Cc'ed Alex and Chen-Yu in case they're investigating breakage
on Rockchip SoCs with linux-next

> Fixes: 6594988fd625 ("clk: composite: Use rate_ops.determine_rate when also a mux is available")
> Signed-off-by: Alexander Stein <alexander.stein@...tq-group.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>


Best regards,
Martin