The system hangs when any of these clocks are turned off.
With the introduction of pinctrl clock support [1], the approach taken
in this clock driver for the APM clocks to rely solely on the
clk_ignore_unused kernel command line option does not work anymore and
the system hangs during boot.
gout_apm_func is a parent clock to the clocks that are going to be
handled by the pinctrl driver [2], namely
gout_apm_apbif_gpio_alive_pclk and gout_apm_apbif_gpio_far_alive_pclk.
It also is the parent to the clocks marked as critical in this commit
here (and some others that aren't relevant for this commit)). This
means that once the pinctrl driver decides to turn off clocks, the
clock framework will subsequently turn off parent clocks of those
pinctrl clocks if they have no (apparent) user. Since gout_apm_func is
the parent, and since no drivers are hooked up to it or any of its
other children, gout_apm_func will be turned off. This will cause the
system to hang, as the clocks marked as critical in this commit stop
having an input.
We might have to add a driver for these clocks, but in the meantime
let's just ensure they stay on even if siblings are turned off.
For the avoidance of doubt: This commit doesn't mean that we can boot
with clk_ignore_unused.
Link: https://lore.kernel.org/r/[email protected] [1]
Link: https://lore.kernel.org/r/20240429-samsung-pinctrl-busclock-dts-v1-0-5e935179f3ca@linaro.org [2]
Signed-off-by: André Draszik <[email protected]>
---
drivers/clk/samsung/clk-gs101.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/clk/samsung/clk-gs101.c b/drivers/clk/samsung/clk-gs101.c
index 05129c3b2f68..e2a6a1992505 100644
--- a/drivers/clk/samsung/clk-gs101.c
+++ b/drivers/clk/samsung/clk-gs101.c
@@ -1896,16 +1896,16 @@ static const struct samsung_gate_clock apm_gate_clks[] __initconst = {
CLK_CON_GAT_GOUT_BLK_APM_UID_UASC_G_SWD_IPCLKPORT_PCLK, 21, 0, 0),
GATE(CLK_GOUT_APM_UASC_P_APM_ACLK,
"gout_apm_uasc_p_apm_aclk", "gout_apm_func",
- CLK_CON_GAT_GOUT_BLK_APM_UID_UASC_P_APM_IPCLKPORT_ACLK, 21, 0, 0),
+ CLK_CON_GAT_GOUT_BLK_APM_UID_UASC_P_APM_IPCLKPORT_ACLK, 21, CLK_IS_CRITICAL, 0),
GATE(CLK_GOUT_APM_UASC_P_APM_PCLK,
"gout_apm_uasc_p_apm_pclk", "gout_apm_func",
- CLK_CON_GAT_GOUT_BLK_APM_UID_UASC_P_APM_IPCLKPORT_PCLK, 21, 0, 0),
+ CLK_CON_GAT_GOUT_BLK_APM_UID_UASC_P_APM_IPCLKPORT_PCLK, 21, CLK_IS_CRITICAL, 0),
GATE(CLK_GOUT_APM_WDT_APM_PCLK,
"gout_apm_wdt_apm_pclk", "gout_apm_func",
CLK_CON_GAT_GOUT_BLK_APM_UID_WDT_APM_IPCLKPORT_PCLK, 21, 0, 0),
GATE(CLK_GOUT_APM_XIU_DP_APM_ACLK,
"gout_apm_xiu_dp_apm_aclk", "gout_apm_func",
- CLK_CON_GAT_GOUT_BLK_APM_UID_XIU_DP_APM_IPCLKPORT_ACLK, 21, 0, 0),
+ CLK_CON_GAT_GOUT_BLK_APM_UID_XIU_DP_APM_IPCLKPORT_ACLK, 21, CLK_IS_CRITICAL, 0),
};
static const struct samsung_cmu_info apm_cmu_info __initconst = {
---
base-commit: d04466706db5e241ee026f17b5f920e50dee26b5
change-id: 20240430-gs101-apm-clocks-fb0918ceaecb
Best regards,
--
André Draszik <[email protected]>
On 4/30/24 10:54, André Draszik wrote:
> The system hangs when any of these clocks are turned off.
>
> With the introduction of pinctrl clock support [1], the approach taken
> in this clock driver for the APM clocks to rely solely on the
> clk_ignore_unused kernel command line option does not work anymore and
> the system hangs during boot.
>
> gout_apm_func is a parent clock to the clocks that are going to be
> handled by the pinctrl driver [2], namely
> gout_apm_apbif_gpio_alive_pclk and gout_apm_apbif_gpio_far_alive_pclk.
> It also is the parent to the clocks marked as critical in this commit
> here (and some others that aren't relevant for this commit)). This
> means that once the pinctrl driver decides to turn off clocks, the
> clock framework will subsequently turn off parent clocks of those
> pinctrl clocks if they have no (apparent) user. Since gout_apm_func is
> the parent, and since no drivers are hooked up to it or any of its
> other children, gout_apm_func will be turned off. This will cause the
> system to hang, as the clocks marked as critical in this commit stop
> having an input.
>
> We might have to add a driver for these clocks, but in the meantime
> let's just ensure they stay on even if siblings are turned off.
It's sane, yes.
>
> For the avoidance of doubt: This commit doesn't mean that we can boot
> with clk_ignore_unused.
>
s/with/without. Because there are still other clocks that are not yet
handled/marked as critical where needed. There's still work to do.
With the typo addressed:
Reviewed-by: Tudor Ambarus <[email protected]>
On Tue, 30 Apr 2024 10:54:59 +0100, André Draszik wrote:
> The system hangs when any of these clocks are turned off.
>
> With the introduction of pinctrl clock support [1], the approach taken
> in this clock driver for the APM clocks to rely solely on the
> clk_ignore_unused kernel command line option does not work anymore and
> the system hangs during boot.
>
> [...]
Applied, thanks!
[1/1] clk: samsung: gs101: mark some apm UASC and XIU clocks critical
https://git.kernel.org/krzk/linux/c/6b32d7474e9b833dc7fadc1b4d4f08af9bd87fde
Best regards,
--
Krzysztof Kozlowski <[email protected]>
On 02/05/2024 09:03, Tudor Ambarus wrote:
>> We might have to add a driver for these clocks, but in the meantime
>> let's just ensure they stay on even if siblings are turned off.
>
> It's sane, yes.
>
>>
>> For the avoidance of doubt: This commit doesn't mean that we can boot
>> with clk_ignore_unused.
>>
>
> s/with/without. Because there are still other clocks that are not yet
> handled/marked as critical where needed. There's still work to do.
>
> With the typo addressed:
Thanks, applied with fix above.
Best regards,
Krzysztof