Re: [PATCH v4 1/5] clk: sunxi-ng: common: Support minimum and maximum rate

["Måns Rullgård" <mans@mansr.com>]

Frank Oltmanns <frank@oltmanns.dev> 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@kernel.org>
> Signed-off-by: Frank Oltmanns <frank@oltmanns.dev>
> Cc: stable@vger.kernel.org
> ---
>  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.

> 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