[PATCH] clk: bcm2835: Make peripheral PLLC critical

[PATCH] clk: bcm2835: Make peripheral PLLC critical

[Maxime Ripard]

When testing for a series affecting the VEC, it was discovered that
turning off and on the VEC clock is crashing the system.

It turns out that, when disabling the VEC clock, it's the only child of
the PLLC-per clock which will also get disabled. The source of the crash
is PLLC-per being disabled.

It's likely that some other device might not take a clock reference that
it actually needs, but it's unclear which at this point. Let's make
PLLC-per critical so that we don't have that crash.

Reported-by: Noralf Trønnes <noralf@tronnes.org>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
---
 drivers/clk/bcm/clk-bcm2835.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clk/bcm/clk-bcm2835.c b/drivers/clk/bcm/clk-bcm2835.c
index 48a1eb9f2d55..19de0e83b65d 100644
--- a/drivers/clk/bcm/clk-bcm2835.c
+++ b/drivers/clk/bcm/clk-bcm2835.c
@@ -1784,7 +1784,7 @@ static const struct bcm2835_clk_desc clk_desc_array[] = {
 		.load_mask = CM_PLLC_LOADPER,
 		.hold_mask = CM_PLLC_HOLDPER,
 		.fixed_divider = 1,
-		.flags = CLK_SET_RATE_PARENT),
+		.flags = CLK_IS_CRITICAL | CLK_SET_RATE_PARENT),
 
 	/*
 	 * PLLD is the display PLL, used to drive DSI display panels.
-- 
2.37.3

Re: [PATCH] clk: bcm2835: Make peripheral PLLC critical

[Stefan Wahren]

Am 26.09.22 um 10:45 schrieb Maxime Ripard:
> When testing for a series affecting the VEC, it was discovered that
> turning off and on the VEC clock is crashing the system.
>
> It turns out that, when disabling the VEC clock, it's the only child of
> the PLLC-per clock which will also get disabled. The source of the crash
> is PLLC-per being disabled.
>
> It's likely that some other device might not take a clock reference that
> it actually needs, but it's unclear which at this point. Let's make
> PLLC-per critical so that we don't have that crash.
>
> Reported-by: Noralf Trønnes <noralf@tronnes.org>
> Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Reviewed-by: Stefan Wahren <stefan.wahren@i2se.com>

Re: [PATCH] clk: bcm2835: Make peripheral PLLC critical

[Noralf Trønnes]

Den 26.09.2022 10.45, skrev Maxime Ripard:
> When testing for a series affecting the VEC, it was discovered that
> turning off and on the VEC clock is crashing the system.
> 
> It turns out that, when disabling the VEC clock, it's the only child of
> the PLLC-per clock which will also get disabled. The source of the crash
> is PLLC-per being disabled.
> 
> It's likely that some other device might not take a clock reference that
> it actually needs, but it's unclear which at this point. Let's make
> PLLC-per critical so that we don't have that crash.
> 
> Reported-by: Noralf Trønnes <noralf@tronnes.org>
> Signed-off-by: Maxime Ripard <maxime@cerno.tech>
> ---

Acked-by: Noralf Trønnes <noralf@tronnes.org>

Re: [PATCH] clk: bcm2835: Make peripheral PLLC critical

[Stephen Boyd]

Quoting Maxime Ripard (2022-09-26 01:45:09)
> When testing for a series affecting the VEC, it was discovered that
> turning off and on the VEC clock is crashing the system.
> 
> It turns out that, when disabling the VEC clock, it's the only child of
> the PLLC-per clock which will also get disabled. The source of the crash
> is PLLC-per being disabled.
> 
> It's likely that some other device might not take a clock reference that
> it actually needs, but it's unclear which at this point. Let's make
> PLLC-per critical so that we don't have that crash.
> 
> Reported-by: Noralf Trønnes <noralf@tronnes.org>
> Signed-off-by: Maxime Ripard <maxime@cerno.tech>
> ---

Applied to clk-next