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: Mon, 21 Jan 2019 19:13:07 +0100	[thread overview]
Message-ID: <1726638.4TPIZlPAWH@jernej-laptop> (raw)
In-Reply-To: <20190121133433.lryqz7ivrj5cxu3g@plaes.org>

Dne ponedeljek, 21. januar 2019 ob 14:34:33 CET je Priit Laes napisal(a):
> On Mon, Jan 21, 2019 at 08:37:29AM +0000, Priit Laes wrote:
> > On Fri, Jan 18, 2019 at 10:51:10PM +0100, Jernej Škrabec wrote:
> > > Dne četrtek, 17. januar 2019 ob 08:24:02 CET je Priit Laes napisal(a):
> > > > On Wed, Jan 16, 2019 at 06:00:32PM +0100, Jernej Škrabec wrote:
> > > > > Dne sreda, 16. januar 2019 ob 13:09:58 CET je Priit Laes napisal(a):
> > > > > > On Thu, Jan 10, 2019 at 06:10:59PM +0100, Jernej Škrabec wrote:
> > > > > > > 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?
> > > > > > 
> > > > > > In both cases I booted from FEL with rootfs on sdcard and tried to
> > > > > > mount
> > > > > > partition from eMMC to /mnt. With your patch, last step it fails.
> > > > > > 
> > > > > > pre-patch working:
> > > > > > pll-ddr-other[768MHz] -> mmc2[512MHz]. (For some reason ahb-mmc2
> > > > > > is
> > > > > > off?)
> > > > > > 
> > > > > > post-patch not working:
> > > > > > pll-periph[600MHz] ->  mmc2[500Mhz], (ahb-mmc2 is enabled)
> > > > > > 
> > > > > > Also, attached the logs.
> > > > > 
> > > > > Thanks. Just one more request. Can you enable debug messages in mmc
> > > > > driver?
> > > > > I'm interested in output of this line:
> > > > > 
> > > > > dev_dbg(mmc_dev(mmc), "setting clk to %d, rounded %ld\n",
> > > > > 
> > > > > 		clock, rate);
> > > > 
> > > > 1c11000 is eMMC:
> > > > [snip]
> > > > [    1.961644] sunxi-mmc 1c11000.mmc: setting clk to 400000, rounded
> > > > 400000
> > > > [    2.004091] sunxi-mmc 1c11000.mmc: setting clk to 400000, rounded
> > > > 400000
> > > > [    2.020296] sunxi-mmc 1c11000.mmc: setting clk to 400000, rounded
> > > > 400000
> > > > [    2.039917] sunxi-mmc 1c11000.mmc: setting clk to 400000, rounded
> > > > 400000
> > > > [    2.047847] sunxi-mmc 1c11000.mmc: setting clk to 400000, rounded
> > > > 400000
> > > > [    2.055053] sunxi-mmc 1c11000.mmc: setting clk to 400000, rounded
> > > > 400000
> > > > [    2.065256] sunxi-mmc 1c11000.mmc: setting clk to 400000, rounded
> > > > 400000
> > > > [    2.092351] sunxi-mmc 1c11000.mmc: setting clk to 400000, rounded
> > > > 400000
> > > > [    2.168725] sunxi-mmc 1c11000.mmc: setting clk to 400000, rounded
> > > > 400000
> > > > [    2.189403] sunxi-mmc 1c11000.mmc: setting clk to 52000000, rounded
> > > > 52000000 [    2.203340] sunxi-mmc 1c11000.mmc: setting clk to
> > > > 52000000,
> > > > rounded 52000000 [    2.211412] sunxi-mmc 1c11000.mmc: setting clk to
> > > > 52000000, rounded 52000000 [    4.967865] sunxi-mmc 1c11000.mmc:
> > > > setting
> > > > clk to 52000000, rounded 52000000 [    8.755345] sunxi-mmc
> > > > 1c11000.mmc:
> > > > setting clk to 52000000, rounded 52000000 [    9.082510] sunxi-mmc
> > > > 1c11000.mmc: setting clk to 52000000, rounded 52000000
> > > > 
> > > > Here I tried to mount partition from eMMC...
> > > > 
> > > > [   72.167311] sunxi-mmc 1c11000.mmc: setting clk to 52000000, rounded
> > > > 52000000 [   72.269629] sunxi-mmc 1c11000.mmc: data error, sending
> > > > stop
> > > > command [   73.268999] sunxi-mmc 1c11000.mmc: send stop command failed
> > > > [/snip]
> > > > 
> > > > And clock tree:
> > > > [snip]
> > > > pll-periph-base                3        3        0  1200000000        
> > > >  0
> > > > 
> > > >  0  50000 pll-periph                  6        6        0   600000000
> > > >  
> > > >    0     0  50000 mmc2                     3        3        0   
> > > >    50000000
> > > >    
> > > >         0     0  50000 mmc2_sample           1        1        0
> > > > 
> > > > 50000000          0   120  50000 mmc2_output           1        1     
> > > >   0
> > > > 
> > > >   50000000          0    60  50000 ahb                     18       18
> > > >   0   300000000          0     0  50000 ahb-mmc2              1       
> > > >   1
> > > >   
> > > >     0   300000000          0     0  50000 [/snip]
> > > > 
> > > > And without patch:
> > > > [snip]
> > > > [    2.003341] sunxi-mmc 1c11000.mmc: XXX: setting clk to 400000,
> > > > rounded
> > > > 400000 [    2.019479] sunxi-mmc 1c11000.mmc: XXX: setting clk to
> > > > 400000,
> > > > rounded 400000 [    2.039144] sunxi-mmc 1c11000.mmc: XXX: setting clk
> > > > to
> > > > 400000, rounded 400000 [    2.047129] sunxi-mmc 1c11000.mmc: XXX:
> > > > setting
> > > > clk to 400000, rounded 400000 [    2.054324] sunxi-mmc 1c11000.mmc:
> > > > XXX:
> > > > setting clk to 400000, rounded 400000 [    2.064481] sunxi-mmc
> > > > 1c11000.mmc:
> > > > XXX: setting clk to 400000, rounded 400000 [    2.091624] sunxi-mmc
> > > > 1c11000.mmc: XXX: setting clk to 400000, rounded 400000 [    2.168067]
> > > > sunxi-mmc 1c11000.mmc: XXX: setting clk to 400000, rounded 400000 [
> > > > 2.188239] sunxi-mmc 1c11000.mmc: XXX: setting clk to 52000000, rounded
> > > > 51200000 [    2.202779] sunxi-mmc 1c11000.mmc: XXX: setting clk to
> > > > 52000000, rounded 51200000 [    2.210817] sunxi-mmc 1c11000.mmc: XXX:
> > > > setting clk to 52000000, rounded 51200000 [    5.103358] sunxi-mmc
> > > > 1c11000.mmc: XXX: setting clk to 52000000, rounded 51200000 [   
> > > > 8.950237]
> > > > sunxi-mmc 1c11000.mmc: XXX: setting clk to 52000000, rounded 51200000
> > > > [
> > > > 9.376201] sunxi-mmc 1c11000.mmc: XXX: setting clk to 52000000, rounded
> > > > 51200000 [  113.618387] sunxi-mmc 1c11000.mmc: XXX: setting clk to
> > > > 52000000, rounded 51200000 [  113.707979] EXT4-fs (mmcblk1p4):
> > > > recovery
> > > > complete
> > > > [  113.728162] EXT4-fs (mmcblk1p4): mounted filesystem with ordered
> > > > data
> > > > mode. Opts: (null) [/snip]
> > > > 
> > > > And clock tree:
> > > > [snip]
> > > > pll-ddr-base                   2        2        0   768000000        
> > > >  0
> > > > 
> > > >  0  50000 pll-ddr-other               1        1        0   768000000
> > > >  
> > > >    0     0  50000 mmc2                     0        0        0   
> > > >    51200000
> > > >    
> > > >         0     0  50000 mmc2_sample           0        0        0
> > > > 
> > > > 51200000          0   120  50000 mmc2_output           0        0     
> > > >   0
> > > > 
> > > >   51200000          0    72  50000 [/snip]
> > > 
> > > It seems to me that clock rate is set properly. It's even better than
> > > before since there is no error between wanted and real clock. I bet
> > > that if you call clk_get_rate() directly behind clk_set_rate() in mmc
> > > driver, you'll get correct value.
> > > 
> > > However, it seems that at some point some other peripheral changes it's
> > > parent clock rate, which inadvertely changes emmc2 clock rate too. The
> > > only possible clock which could interfere is sata. Can you disable
> > > driver in you kernel config and try again?
> > 
> > OK, tried following things in succession, but SATA disabling does not
> > work:
> > 
> > a) Marked all ahci stuff in devicetree as disabled
> > b) Disable CONFIG_AHCI_SUNXI in kernel
> > c) Even disabled SATA stuff in u-boot
> 
> But it works, when I allow mmc2 clock to set parent rate:

Strange, I checked both pre- and post- patch clk_summary you sent me and in 
both cases both mmc2 parent clocks have same rate as before. This would need a 
more detailed analysis with a lot of debug print, but don't have such board.

CLK_SET_PARENT rate might be viable solution, but  you have to be sure that 
any clock using pll-periph as a parent is in expected range.

On the plus side, if this works, eMMC will work faster due to 8 MHz clock rate 
increase :)

> 
> pll-periph-base                3        3        0   312000000          0   
>  0  50000 mbus                        1        1        0    78000000      
>    0     0  50000 pll-periph-sata             1        1        0   
> 26000000          0     0  50000 sata                     1        1       
> 0    26000000          0     0  50000 pll-periph                  5       
> 5        0   156000000          0     0  50000 mmc2                     0  
>      0        0    52000000          0     0  50000 mmc2_sample           0
>        0        0    52000000          0   120  50000 mmc2_output          
> 0        0        0    52000000          0   120  50000 mmc0               
>      0        0        0    39000000          0     0  50000 mmc0_sample   
>        0        0        0    39000000          0    90  50000 mmc0_output 
>          0        0        0    39000000          0    90  50000
> 
> 
> Now, what I don't understand is why the `enable count` does not increase :(

mmc has suspend/resume functionality which might power down mmc when not in 
use and thus disable clocks. Try initiate some big transfer from/to eMMC and 
check clocks in between.

BR,
Jernej

> 
> ---
> diff --git a/drivers/clk/sunxi-ng/ccu-sun4i-a10.c
> b/drivers/clk/sunxi-ng/ccu-sun4i-a10.c index 129ebd2588fd..605e13b4ef90
> 100644
> --- a/drivers/clk/sunxi-ng/ccu-sun4i-a10.c
> +++ b/drivers/clk/sunxi-ng/ccu-sun4i-a10.c
> @@ -498,7 +498,7 @@ static SUNXI_CCU_MP_WITH_MUX_GATE(mmc2_clk, "mmc2",
> mod0_default_parents, 0x090, 16, 2,        /* P */
>                                   24, 2,        /* mux */
>                                   BIT(31),      /* gate */
> -                                 0);
> +                                 CLK_SET_RATE_PARENT);
> 
>  /* MMC output and sample clocks are not present on A10 */
>  static SUNXI_CCU_PHASE(mmc2_output_clk, "mmc2_output", "mmc2",
> 
> > > Best regards,
> > > Jernej