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

Priit Laes
2019-01-21T08:37:29Z

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

>
> Best regards,
> Jernej