Re: [PATCH v4 1/5] clk: sunxi-ng: common: Support minimum and maximum rate
From: Frank Oltmanns
Date: Wed May 22 2024 - 02:33:35 EST
Hi Måns,
21.05.2024 15:43:10 Måns Rullgård <mans@xxxxxxxxx>:
> Frank Oltmanns <frank@xxxxxxxxxxxx> writes:
>
>> The Allwinner SoC's typically have an upper and lower limit for their
>> clocks' rates. Up until now, support for that has been implemented
>> separately for each clock type.
>>
>> Implement that functionality in the sunxi-ng's common part making use of
>> the CCF rate liming capabilities, so that it is available for all clock
>> types.
>>
>> Suggested-by: Maxime Ripard <mripard@xxxxxxxxxx>
>> Signed-off-by: Frank Oltmanns <frank@xxxxxxxxxxxx>
>> Cc: stable@xxxxxxxxxxxxxxx
>> ---
>> drivers/clk/sunxi-ng/ccu_common.c | 19 +++++++++++++++++++
>> drivers/clk/sunxi-ng/ccu_common.h | 3 +++
>> 2 files changed, 22 insertions(+)
>
> This just landed in 6.6 stable, and it broke HDMI output on an A20 based
> device, the clocks ending up all wrong as seen in this diff of
> /sys/kernel/debug/clk/clk_summary:
>
> @@ -70,16 +71,14 @@
> apb1-i2c0 0 0 0 24000000 0
>
> pll-gpu 0 0 0 1200000000 0
> - pll-video1 3 3 1 159000000 0
> + pll-video1 2 2 1 159000000 0
> hdmi 1 1 0 39750000 0
>
> tcon0-ch1-sclk2 1 1 1 39750000 0
> tcon0-ch1-sclk1 1 1 1 39750000 0
>
> - pll-video1-2x 1 1 0 318000000 0
> + pll-video1-2x 0 0 0 318000000 0
>
> - hdmi-tmds 2 2 0 39750000 0
> - hdmi-ddc 1 1 0 1987500 0
> pll-periph-base 2 2 0 1200000000 0
> mbus 1 1 0 300000000 0
> pll-periph-sata 0 0 0 100000000 0
> @@ -199,7 +198,7 @@
>
> ace 0 0 0 384000000 0
> ve 0 0 0 384000000 0
> - pll-video0 4 4 2 297000000 0
> + pll-video0 5 5 2 297000000 0
> hdmi1 0 0 0 297000000 0
> tcon1-ch1-sclk2 0 0 0 297000000 0
> tcon1-ch1-sclk1 0 0 0 297000000 0
> @@ -222,8 +221,10 @@
>
> de-be0 1 1 1 297000000 0
>
> - pll-video0-2x 0 0 0 594000000 0
> + pll-video0-2x 1 1 0 594000000 0
>
> + hdmi-tmds 2 2 0 594000000 0
> + hdmi-ddc 1 1 0 29700000 0
> pll-audio-base 0 0 0 1500000 0
> pll-audio-8x 0 0 0 3000000 0
> i2s2 0 0 0 3000000 0
>
> Reverting this commit makes it work again.
Thank you for your detailed report!
I've had a first look at hdmi-tmds and hdmi-ddc, and neither seems to be calling ccu_is_better_rate() in their determine_rate() functions. Their parents have the exact same rates in your diff, so, my current working assumption is that they can't be the cause either.
I'll have a more detailed look over the weekend. Until then, if anyone has some ideas where I should have a look next, please share your thoughts.
Best regards,
Frank
>
>> diff --git a/drivers/clk/sunxi-ng/ccu_common.c b/drivers/clk/sunxi-ng/ccu_common.c
>> index 8babce55302f..ac0091b4ce24 100644
>> --- a/drivers/clk/sunxi-ng/ccu_common.c
>> +++ b/drivers/clk/sunxi-ng/ccu_common.c
>> @@ -44,6 +44,16 @@ bool ccu_is_better_rate(struct ccu_common *common,
>> unsigned long current_rate,
>> unsigned long best_rate)
>> {
>> + unsigned long min_rate, max_rate;
>> +
>> + clk_hw_get_rate_range(&common->hw, &min_rate, &max_rate);
>> +
>> + if (current_rate > max_rate)
>> + return false;
>> +
>> + if (current_rate < min_rate)
>> + return false;
>> +
>> if (common->features & CCU_FEATURE_CLOSEST_RATE)
>> return abs(current_rate - target_rate) < abs(best_rate - target_rate);
>>
>> @@ -122,6 +132,7 @@ static int sunxi_ccu_probe(struct sunxi_ccu *ccu, struct device *dev,
>>
>> for (i = 0; i < desc->hw_clks->num ; i++) {
>> struct clk_hw *hw = desc->hw_clks->hws[i];
>> + struct ccu_common *common = hw_to_ccu_common(hw);
>> const char *name;
>>
>> if (!hw)
>> @@ -136,6 +147,14 @@ static int sunxi_ccu_probe(struct sunxi_ccu *ccu, struct device *dev,
>> pr_err("Couldn't register clock %d - %s\n", i, name);
>> goto err_clk_unreg;
>> }
>> +
>> + if (common->max_rate)
>> + clk_hw_set_rate_range(hw, common->min_rate,
>> + common->max_rate);
>> + else
>> + WARN(common->min_rate,
>> + "No max_rate, ignoring min_rate of clock %d - %s\n",
>> + i, name);
>> }
>>
>> ret = of_clk_add_hw_provider(node, of_clk_hw_onecell_get,
>> diff --git a/drivers/clk/sunxi-ng/ccu_common.h b/drivers/clk/sunxi-ng/ccu_common.h
>> index 942a72c09437..329734f8cf42 100644
>> --- a/drivers/clk/sunxi-ng/ccu_common.h
>> +++ b/drivers/clk/sunxi-ng/ccu_common.h
>> @@ -31,6 +31,9 @@ struct ccu_common {
>> u16 lock_reg;
>> u32 prediv;
>>
>> + unsigned long min_rate;
>> + unsigned long max_rate;
>> +
>> unsigned long features;
>> spinlock_t *lock;
>> struct clk_hw hw;
>>
>> --
>>
>> 2.44.0
>>
>
> --
> Måns Rullgård