Re: GPMI iMX6ull timeout on DMA

[Miquel Raynal <miquel.raynal@xxxxxxxxxxx>]

Hi Greg,

One question below.

+Michael
+Sascha

Hello Michael, here is a similar issue to yours, I know you did not
have enough time to share your solution but here we have someone else
reproducing the issue, would you mind sharing a branch or a patch, even
a WIP one, just to help debugging?

Greg Ungerer <gerg@xxxxxxxxxx> wrote on Mon, 29 Jul 2019 16:41:51 +1000:

> Hi Miquel,
> 
> I am experiencing a problem with NAND flash DMA timeouts on
> iMX6ull based boards. The problem is very similar to that
> described in:
> 
>    https://linux-mtd.infradead.narkive.com/JIUulfFB/gpmi-imx6ull-timeout-on-dma
> 
> That didn't come to any specific resolution that I could see
> in that thread.
> 
> The boot trace on the console for me looks like this:
> 
> nand: device found, Manufacturer ID: 0x2c, Chip ID: 0xda
> nand: Micron MT29F2G08ABAEAWP
> nand: 256 MiB, SLC, erase size: 128 KiB, page size: 2048, OOB size: 64
> gpmi-nand 1806000.gpmi-nand: DMA timeout, last DMA
> gpmi-nand 1806000.gpmi-nand: Show GPMI registers :
> gpmi-nand 1806000.gpmi-nand: offset 0x000 : 0x20830002
> gpmi-nand 1806000.gpmi-nand: offset 0x010 : 0x00000000
> gpmi-nand 1806000.gpmi-nand: offset 0x020 : 0x00000000
> gpmi-nand 1806000.gpmi-nand: offset 0x030 : 0x00000000
> gpmi-nand 1806000.gpmi-nand: offset 0x040 : 0x00000000
> gpmi-nand 1806000.gpmi-nand: offset 0x050 : 0x00000000
> gpmi-nand 1806000.gpmi-nand: offset 0x060 : 0x01c6800c
> gpmi-nand 1806000.gpmi-nand: offset 0x070 : 0x00010101
> gpmi-nand 1806000.gpmi-nand: offset 0x080 : 0xe0000000
> gpmi-nand 1806000.gpmi-nand: offset 0x090 : 0x23023336
> gpmi-nand 1806000.gpmi-nand: offset 0x0a0 : 0x000001ee
> gpmi-nand 1806000.gpmi-nand: offset 0x0b0 : 0xff000001
> gpmi-nand 1806000.gpmi-nand: offset 0x0c0 : 0x00000001
> gpmi-nand 1806000.gpmi-nand: offset 0x0d0 : 0x05020000
> gpmi-nand 1806000.gpmi-nand: Show BCH registers :
> gpmi-nand 1806000.gpmi-nand: offset 0x000 : 0x00000100
> gpmi-nand 1806000.gpmi-nand: offset 0x010 : 0x00000010
> gpmi-nand 1806000.gpmi-nand: offset 0x020 : 0x00000000
> gpmi-nand 1806000.gpmi-nand: offset 0x030 : 0x00000000
> gpmi-nand 1806000.gpmi-nand: offset 0x040 : 0x00000000
> gpmi-nand 1806000.gpmi-nand: offset 0x050 : 0x00000000
> gpmi-nand 1806000.gpmi-nand: offset 0x060 : 0x00000000
> gpmi-nand 1806000.gpmi-nand: offset 0x070 : 0x00000000
> gpmi-nand 1806000.gpmi-nand: offset 0x080 : 0x030a2080
> gpmi-nand 1806000.gpmi-nand: offset 0x090 : 0x083e2080
> gpmi-nand 1806000.gpmi-nand: offset 0x0a0 : 0x070a4080
> gpmi-nand 1806000.gpmi-nand: offset 0x0b0 : 0x10da4080
> gpmi-nand 1806000.gpmi-nand: offset 0x0c0 : 0x070a4080
> gpmi-nand 1806000.gpmi-nand: offset 0x0d0 : 0x10da4080
> gpmi-nand 1806000.gpmi-nand: offset 0x0e0 : 0x070a4080
> gpmi-nand 1806000.gpmi-nand: offset 0x0f0 : 0x10da4080
> gpmi-nand 1806000.gpmi-nand: offset 0x100 : 0x00000000
> gpmi-nand 1806000.gpmi-nand: offset 0x110 : 0x00000000
> gpmi-nand 1806000.gpmi-nand: offset 0x120 : 0x00000000
> gpmi-nand 1806000.gpmi-nand: offset 0x130 : 0x00000000
> gpmi-nand 1806000.gpmi-nand: offset 0x140 : 0x00000000
> gpmi-nand 1806000.gpmi-nand: offset 0x150 : 0x20484342
> gpmi-nand 1806000.gpmi-nand: offset 0x160 : 0x01000000
> gpmi-nand 1806000.gpmi-nand: offset 0x170 : 0x00000000
> gpmi-nand 1806000.gpmi-nand: BCH Geometry :
> GF length              : 13
> ECC Strength           : 8
> Page Size in Bytes     : 2110
> Metadata Size in Bytes : 10
> ECC Chunk0 Size in Bytes: 512
> ECC Chunkn Size in Bytes: 512
> ECC Chunk Count        : 4
> Payload Size in Bytes  : 2048
> Auxiliary Size in Bytes: 16
> Auxiliary Status Offset: 12
> Block Mark Byte Offset : 1999
> Block Mark Bit Offset  : 0
> gpmi-nand 1806000.gpmi-nand: Chip: 0, Error -110
> nand: timing mode 5 not acknowledged by the NAND chip

What is the final timing mode used? Most of us tested in mode 5 I
guess, maybe mode 4 is broken (don't know if this is the one used here,
neither why mode 5 is refused). Can you please try by limiting the mode
to 0, 1, 2... until, hopefully, we narrow down to the failing mode.

> gpmi-nand 1806000.gpmi-nand: Chip: 0, Error -22
> Scanning device for bad blocks
> gpmi-nand 1806000.gpmi-nand: Chip: 0, Error -22
> gpmi-nand 1806000.gpmi-nand: Chip: 0, Error -22
> gpmi-nand 1806000.gpmi-nand: Chip: 0, Error -22
> gpmi-nand 1806000.gpmi-nand: Chip: 0, Error -22
> ....
> gpmi-nand 1806000.gpmi-nand: Chip: 0, Error -22
> gpmi-nand 1806000.gpmi-nand: Chip: 0, Error -22
> gpmi-nand 1806000.gpmi-nand: Chip: 0, Error -22
> 5 fixed-partitions partitions found on MTD device gpmi-nand
> Creating 5 MTD partitions on "gpmi-nand":
> 0x000000000000-0x000000500000 : "u-boot"
> 0x000000500000-0x000000600000 : "u-boot-env"
> 0x000000600000-0x000000800000 : "log"
> 0x000000800000-0x000010000000 : "flash"
> 0x000000000000-0x000010000000 : "all"
> gpmi-nand 1806000.gpmi-nand: driver registered.
> 
> 
> This is using a linux kernel v5.1.14. I have seen this happen on
> a number of boards I have here - but it is only occasional. It
> only happens once in a while on boot, maybe 1 in 40 or more times.
> So it can take quite a while to reproduce (using a boot loop setup).

That's strange... I don't get what would produce such unstable issue.

> 
> As per the email thread I pointed to above I looked at reverting
> those patches, but that was not at all easy given how much the gpmi
> driver code had moved. So instead I modified the code with this:
> 
> --- a/linux/drivers/mtd/nand/raw/gpmi-nand/gpmi-lib.c
> +++ b/linux/drivers/mtd/nand/raw/gpmi-nand/gpmi-lib.c
> @@ -481,6 +481,7 @@ static void gpmi_nfc_compute_timings(struct gpmi_nand_data *this,
>     void gpmi_nfc_apply_timings(struct gpmi_nand_data *this)
>   {
> +#if 0
>          struct gpmi_nfc_hardware_timing *hw = &this->hw;
>          struct resources *r = &this->resources;
>          void __iomem *gpmi_regs = r->gpmi_regs;
> @@ -505,6 +512,7 @@ void gpmi_nfc_apply_timings(struct gpmi_nand_data *this)
>            /* Wait for the DLL to settle. */
>          udelay(dll_wait_time_us);
> +#endif
>   }
>     int gpmi_setup_data_interface(struct nand_chip *chip, int chipnr,
> 
> So far after a couple of days of testing with this I no longer
> see the DMA timeout.
> 
> Any thoughts?
> 
> Regards
> Greg
> 

Thanks,
Miquèl

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