Re: [linux-sunxi] [PATCH v3 02/28] clk: sunxi-ng: Adjust MP clock parent rate when allowed

[Priit Laes <plaes@plaes.org>]

On Sun, Nov 04, 2018 at 07:26:39PM +0100, Jernej Skrabec wrote:
> Currently MP clocks don't consider adjusting parent rate even if they
> are allowed to do so. Such behaviour considerably lowers amount of
> possible rates, which is very inconvenient when such clock is used for
> pixel clock, for example.
> 
> In order to improve the situation, adjusting parent rate is considered
> when allowed.
> 
> This code is inspired by clk_divider_bestdiv() function, which does
> basically the same thing for different clock type.

This patch seems to break the eMMC support on Olinuxino-Lime2-eMMC boards:

EXT4-fs (mmcblk1p4): INFO: recovery required on readonly filesystem
EXT4-fs (mmcblk1p4): write access will be enabled during recovery
sunxi-mmc 1c11000.mmc: data error, sending stop command
sunxi-mmc 1c11000.mmc: send stop command failed


$ git bisect log
git bisect start
# good: [3df407b2a5346db1c48809706ece7a8616c79e0b] mmc: dw_mmc-bluefield: simplify the probe() function
git bisect good 3df407b2a5346db1c48809706ece7a8616c79e0b
# bad: [00d59fde8532b2d42e80909d2e58678755e04da9] Merge tag 'mmc-v4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc
git bisect bad 00d59fde8532b2d42e80909d2e58678755e04da9
# good: [01e421feec0817bb3141eaae4c517410d193d440] Merge branch 'fixes' into next
git bisect good 01e421feec0817bb3141eaae4c517410d193d440
# bad: [1eefdec18eded41833401cfd64749643ff72e7da] Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
git bisect bad 1eefdec18eded41833401cfd64749643ff72e7da
# good: [eaa76499711535fd64d747cc4ef0d78ab0fd41c6] Merge tag 'mtd/for-4.21' of git://git.infradead.org/linux-mtd
git bisect good eaa76499711535fd64d747cc4ef0d78ab0fd41c6
# good: [4e4390ad067a61ce4e7607bd0df31f19a4caa36a] Merge tag 'leds-for-4.21-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/j.anaszewski/linux-leds
git bisect good 4e4390ad067a61ce4e7607bd0df31f19a4caa36a
# bad: [c2f1f3e0e17d94ab0c66d83e669492cb9e9a3698] Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-next
git bisect bad c2f1f3e0e17d94ab0c66d83e669492cb9e9a3698
# bad: [e4b99d415c3908581d4703203e1e805f043a3e71] Merge branch 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
git bisect bad e4b99d415c3908581d4703203e1e805f043a3e71
# bad: [ffe05540d18013db62c43627836a3638e9a2c7aa] Merge branches 'clk-renesas', 'clk-allwinner', 'clk-tegra', 'clk-meson' and 'clk-rockchip' into clk-next
git bisect bad ffe05540d18013db62c43627836a3638e9a2c7aa
# good: [1a501c8defe950571316d5ddd917bf44f5ed7bd4] Merge branches 'clk-managed-registration', 'clk-spdx', 'clk-remove-basic' and 'clk-ops-const' into clk-next
git bisect good 1a501c8defe950571316d5ddd917bf44f5ed7bd4
# good: [e74581b79ddd9b49b8c61e2791fc4dffc0245afb] Merge tag 'meson-clk-4.21-2' of https://github.com/BayLibre/clk-meson into clk-meson
git bisect good e74581b79ddd9b49b8c61e2791fc4dffc0245afb
# good: [60baf75e3f5b76043c25328ac0c5320aaef5ea41] Merge tag 'clk-renesas-for-v4.21-tag2' of git://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers into clk-renesas
git bisect good 60baf75e3f5b76043c25328ac0c5320aaef5ea41
# bad: [a41f85b6017ee20952a60e4330bcae2527fe2c2a] Merge tag 'sunxi-clk-for-4.21' of https://git.kernel.org/pub/scm/linux/kernel/git/sunxi/linux into clk-allwinner
git bisect bad a41f85b6017ee20952a60e4330bcae2527fe2c2a
# bad: [ee678706e46d0d185c27cc214ad97828e0643159] clk: sunxi-ng: a64: Fix gate bit of DSI DPHY
git bisect bad ee678706e46d0d185c27cc214ad97828e0643159
# bad: [65b6657672388b72822e0367f06d41c1e3ffb5bb] clk: sunxi-ng: Use u64 for calculation of NM rate
git bisect bad 65b6657672388b72822e0367f06d41c1e3ffb5bb
# good: [db7548934603d9eda12649dff97ea5c29884405d] clk: sunxi-ng: sun50i: h6: Fix MMC clock mux width
git bisect good db7548934603d9eda12649dff97ea5c29884405d
# bad: [3f790433c3cb27ecaf2ca0e07ac25964e4fd9f15] clk: sunxi-ng: Adjust MP clock parent rate when allowed
git bisect bad 3f790433c3cb27ecaf2ca0e07ac25964e4fd9f15
# first bad commit: [3f790433c3cb27ecaf2ca0e07ac25964e4fd9f15] clk: sunxi-ng: Adjust MP clock parent rate when allowed


> 
> Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
> ---
>  drivers/clk/sunxi-ng/ccu_mp.c | 64 +++++++++++++++++++++++++++++++++--
>  1 file changed, 62 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/clk/sunxi-ng/ccu_mp.c b/drivers/clk/sunxi-ng/ccu_mp.c
> index 5d0af4051737..0357349eb767 100644
> --- a/drivers/clk/sunxi-ng/ccu_mp.c
> +++ b/drivers/clk/sunxi-ng/ccu_mp.c
> @@ -40,6 +40,61 @@ static void ccu_mp_find_best(unsigned long parent, unsigned long rate,
>  	*p = best_p;
>  }
>  
> +static unsigned long ccu_mp_find_best_with_parent_adj(struct clk_hw *hw,
> +						      unsigned long *parent,
> +						      unsigned long rate,
> +						      unsigned int max_m,
> +						      unsigned int max_p)
> +{
> +	unsigned long parent_rate_saved;
> +	unsigned long parent_rate, now;
> +	unsigned long best_rate = 0;
> +	unsigned int _m, _p, div;
> +	unsigned long maxdiv;
> +
> +	parent_rate_saved = *parent;
> +
> +	/*
> +	 * The maximum divider we can use without overflowing
> +	 * unsigned long in rate * m * p below
> +	 */
> +	maxdiv = max_m * max_p;
> +	maxdiv = min(ULONG_MAX / rate, maxdiv);
> +
> +	for (_p = 1; _p <= max_p; _p <<= 1) {
> +		for (_m = 1; _m <= max_m; _m++) {
> +			div = _m * _p;
> +
> +			if (div > maxdiv)
> +				break;
> +
> +			if (rate * div == parent_rate_saved) {
> +				/*
> +				 * It's the most ideal case if the requested
> +				 * rate can be divided from parent clock without
> +				 * needing to change parent rate, so return the
> +				 * divider immediately.
> +				 */
> +				*parent = parent_rate_saved;
> +				return rate;
> +			}
> +
> +			parent_rate = clk_hw_round_rate(hw, rate * div);
> +			now = parent_rate / div;
> +
> +			if (now <= rate && now > best_rate) {
> +				best_rate = now;
> +				*parent = parent_rate;
> +
> +				if (now == rate)
> +					return rate;
> +			}
> +		}
> +	}
> +
> +	return best_rate;
> +}
> +
>  static unsigned long ccu_mp_round_rate(struct ccu_mux_internal *mux,
>  				       struct clk_hw *hw,
>  				       unsigned long *parent_rate,
> @@ -56,8 +111,13 @@ static unsigned long ccu_mp_round_rate(struct ccu_mux_internal *mux,
>  	max_m = cmp->m.max ?: 1 << cmp->m.width;
>  	max_p = cmp->p.max ?: 1 << ((1 << cmp->p.width) - 1);
>  
> -	ccu_mp_find_best(*parent_rate, rate, max_m, max_p, &m, &p);
> -	rate = *parent_rate / p / m;
> +	if (!(clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT)) {
> +		ccu_mp_find_best(*parent_rate, rate, max_m, max_p, &m, &p);
> +		rate = *parent_rate / p / m;
> +	} else {
> +		rate = ccu_mp_find_best_with_parent_adj(hw, parent_rate, rate,
> +							max_m, max_p);
> +	}
>  
>  	if (cmp->common.features & CCU_FEATURE_FIXED_POSTDIV)
>  		rate /= cmp->fixed_post_div;
> -- 
> 2.19.1
> 
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