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

From: "Jernej Škrabec" <jernej.skrabec@siol.net>
To: Priit Laes <plaes@plaes.org>
Cc: maxime.ripard@bootlin.com, wens@csie.org, robh+dt@kernel.org,
	mturquette@baylibre.com, sboyd@kernel.org, airlied@linux.ie,
	architt@codeaurora.org, a.hajda@samsung.com,
	Laurent.pinchart@ideasonboard.com, devicetree@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org,
	dri-devel@lists.freedesktop.org, linux-sunxi@googlegroups.com
Subject: Re: [linux-sunxi] [PATCH v3 02/28] clk: sunxi-ng: Adjust MP clock parent rate when allowed
Date: Thu, 10 Jan 2019 18:10:59 +0100	[thread overview]
Message-ID: <2085880.8AFF3nNMGQ@jernej-laptop> (raw)
In-Reply-To: <20190110091548.e6btt2qofi7ttt6z@plaes.org>

Dne četrtek, 10. januar 2019 ob 10:15:48 CET je Priit Laes napisal(a):
> 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
> 

I'm not familiar with A20. What is interesting is that emmc clocks don't have 
CLK_SET_RATE_PARENT flag set, so you shouldn't see any difference.

Can you post content of clk_summary with and without this patch?

Best regards,
Jernej

> 
> $ 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;