Re: CHIPPro NAND issue with 4.12 rc1

[Boris Brezillon <boris.brezillon@free-electrons.com>]

Le Sat, 20 May 2017 15:24:06 -0600,
Angus Ainslie <angus@akkea.ca> a écrit :

> On 2017-05-20 09:14, Boris Brezillon wrote:
> > Le Sat, 20 May 2017 08:49:04 -0600,
> > Angus Ainslie <angus@akkea.ca> a écrit :
> >   
> >> Hi All,
> >> 
> >> I'm trying to boot a CHIPPro with the stock 4.12 rc1 kernel. If I make
> >> no modifications to the sun5i-gr8-chip-pro.dtb the kernel boots but
> >> can't find the root partition.
> >> 
> >> So I added the partitions to the dts file
> >> 
> >> diff --git a/arch/arm/boot/dts/sun5i-gr8-chip-pro.dts
> >> b/arch/arm/boot/dts/sun5i-gr8-chip-pro.dts
> >> index c55b11a..0e61e6b 100644
> >> --- a/arch/arm/boot/dts/sun5i-gr8-chip-pro.dts
> >> +++ b/arch/arm/boot/dts/sun5i-gr8-chip-pro.dts
> >> @@ -146,6 +146,32 @@
> >>                  reg = <0>;
> >>                  allwinner,rb = <0>;
> >>                  nand-ecc-mode = "hw";
> >> +    nand-on-flash-bbt;
> >> +
> >> +    spl@0 {
> >> +      label = "SPL";
> >> +      reg = /bits/ 64 <0x0 0x400000>;
> >> +    };
> >> +
> >> +    spl-backup@400000 {
> >> +      label = "SPL.backup";
> >> +      reg = /bits/ 64 <0x400000 0x400000>;
> >> +    };
> >> +
> >> +    u-boot@800000 {
> >> +      label = "U-Boot";
> >> +      reg = /bits/ 64 <0x800000 0x400000>;
> >> +    };
> >> +
> >> +    env@c00000 {
> >> +      label = "env";
> >> +      reg = /bits/ 64 <0xc00000 0x400000>;
> >> +    };
> >> +
> >> +    rootfs@1000000 {
> >> +      label = "rootfs";
> >> +      reg = /bits/ 64 <0x1000000 0x1f000000>;
> >> +    };
> >>          };
> >>   };
> >> 
> >> and now the kernel finds the partition but it times out trying to 
> >> mount
> >> it. It seems to be something in the dts files because if I use the
> >> ntc-gr8-crumb.dts from the ntc 4.4.30 kernel then the system boots all
> >> the way to userland.  
> > 
> > Hm, that's weird. Just changing the dtb makes it work? Did you try to
> > dump both dtbs and figure out what else changes?
> >   
> 
> Yeah I thought it was weird too. I was thinking that maybe the pin muxes 
> were getting changed and the rb net or the interrupt net was getting 
> changed to a different function.
> 
> I did decompile to 2 dtb's and I couldn't find many differences. They 
> were mostly around some pull ups and drive strength for some of the NAND 
> and i2c pins. I tried adding those changes and it still didn't work so I 
> went back to the minimal set of changes to reproduce the bug.
> 
> > Also, I wonder how the NAND is correctly detected without this patch
> > [1].
> >   
> 
> 
> That patch seems to be in my 4.12-rc1 kernel, I have a definition for 
> the TC58NVG2S0H.
> 
> >> 
> >> [    7.130000] ubi0: scanning is finished
> >> [    7.150000] ubi0: attached mtd4 (name "rootfs", size 496 MiB)
> >> [    7.160000] ubi0: PEB size: 262144 bytes (256 KiB), LEB size: 
> >> 258048
> >> bytes
> >> [    7.170000] ubi0: min./max. I/O unit sizes: 4096/4096, sub-page 
> >> size
> >> 1024
> >> [    7.180000] ubi0: VID header offset: 1024 (aligned 1024), data
> >> offset: 4096
> >> [    7.190000] ubi0: good PEBs: 1977, bad PEBs: 7, corrupted PEBs: 0
> >> [    7.200000] ubi0: user volume: 1, internal volumes: 1, max. volumes
> >> count: 128
> >> [    7.210000] ubi0: max/mean erase counter: 3/1, WL threshold: 4096,
> >> image sequence number: 1444477407
> >> [    7.220000] ubi0: available PEBs: 1, total reserved PEBs: 1976, 
> >> PEBs
> >> reserved for bad PEB handling: 33  
> > 
> > UBI attach works...
> >   
> >> [    7.240000] hctosys: unable to open rtc device (rtc0)
> >> [    7.250000] vcc3v0: disabling

Interestingly, it starts failing after the core disables all unused
regulators. Not sure this is related but that's worth having a look.

I looked at the schematics and it seems VCC-3V3 (which is powering the
NAND chip) is enabled with the EXTEN pin of the AXP209 [1]. I don't know
if this pin is controlled by Linux, but maybe you can dump register
0x12 and check if EXTEN is set to 1.

> >> [    7.250000] ALSA device list:
> >> [    7.260000]   #0: sun4i-codec
> >> [    7.260000] ubi0: background thread "ubi_bgt0d" started, PID 53
> >> [    8.320000] sunxi_nand 1c03000.nand: wait interrupt timedout
> >> [    9.320000] sunxi_nand 1c03000.nand: wait interrupt timedout
> >> [   10.330000] sunxi_nand 1c03000.nand: wait for empty cmd FIFO 
> >> timedout
> >> [   11.340000] sunxi_nand 1c03000.nand: wait for empty cmd FIFO 
> >> timedout
> >> [   12.350000] sunxi_nand 1c03000.nand: wait for empty cmd FIFO 
> >> timedout
> >> [   13.360000] sunxi_nand 1c03000.nand: wait for empty cmd FIFO 
> >> timedout
> >> [   14.370000] sunxi_nand 1c03000.nand: wait for empty cmd FIFO 
> >> timedout
> >> [   14.380000] ubi0 warning: ubi_io_read: error -110 while reading 
> >> 4096
> >> bytes from PEB 1034:4096, read only 0 bytes, retry  
> > 
> > And suddenly you get timeouts. That's really weird.  
> 
> 
> Is there anything I can do on this end to help debug ?
> 
> 
> > 
> > [1]https://github.com/NextThingCo/linux/commit/5ebc35ce1223ef14ace9479d5f97d0fce979e550  
> 

[1]http://linux-sunxi.org/AXP209