Re: [RESEND PATCH v3 5/8] mtd: spi-nor: cadence-quadspi: Handle probe deferral while requesting DMA channel

From: Jan Kiszka
Date: Mon Aug 24 2020 - 13:22:26 EST

On 24.08.20 14:49, Jan Kiszka wrote:
> On 24.08.20 13:45, Vignesh Raghavendra wrote:
>>
>>
>> On 8/22/20 11:35 PM, Jan Kiszka wrote:
>>> On 01.06.20 09:04, Vignesh Raghavendra wrote:
>>>> dma_request_chan_by_mask() can throw EPROBE_DEFER if DMA provider
>>>> is not yet probed. Currently driver just falls back to using PIO mode
>>>> (which is less efficient) in this case. Instead return probe deferral
>>>> error as is so that driver will be re probed once DMA provider is
>>>> available.
>>>>
>>>> Signed-off-by: Vignesh Raghavendra <vigneshr@xxxxxx>
>>>> Reviewed-by: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx>
>>>> ---
>> [...]
>>>>
>>>> static const struct spi_nor_controller_ops cqspi_controller_ops = {
>>>> @@ -1269,8 +1274,11 @@ static int cqspi_setup_flash(struct cqspi_st *cqspi, struct device_node *np)
>>>> dev_dbg(nor->dev, "using direct mode for %s\n",
>>>> mtd->name);
>>>>
>>>> - if (!cqspi->rx_chan)
>>>> - cqspi_request_mmap_dma(cqspi);
>>>> + if (!cqspi->rx_chan) {
>>>> + ret = cqspi_request_mmap_dma(cqspi);
>>>> + if (ret == -EPROBE_DEFER)
>>>> + goto err;
>>>> + }
>>>> }
>>>> }
>>>>
>>>>
>>>
>>> This seem to break reading the SPI flash on our IOT2050 [1] (didn't test
>>> the eval board yet).
>>>
>>> Without that commit, read happens via PIO, and that works. With the
>>> commit, the pattern
>>>
>>> with open("out.bin", "wb") as out:
>>> pos = 0
>>> while pos < 2:
>>> with open("/dev/mtd0", "rb") as mtd:
>>> mtd.seek(pos * 0x10000)
>>> out.write(mtd.read(0x10000))
>>> pos += 1
>>>
>>> gives the wrong result for the second block while
>>
>> Interesting... Could you please explain wrong result? Is the data move
>> around or completely garbage?
>
> It looks like some stripes contain data from other parts of the flash or
> kernel RAM. It's not just garbage, there are readable strings included.
>
>>
>> Does this fail even on AM654 EVM? Could you share full script for me to
>> test locally?
>
> The scripts are complete (python). Just binary-diff the outputs.
>
> I'll try on the EVM later.

Done so now, could reproduce.

But the OSPIs are definitely different. EVM reports

spi-nor spi0.0: mt35xu512aba (65536 Kbytes)

with 4K erase size. Our our board, we have

spi-nor spi7.0: w25q128 (16384 Kbytes)

with 64K erase size.

Here is some extract of the hex-diffs between out.bin and out2.bin (the
latter being the good one):

--- /dev/fd/63 2020-08-24 17:16:58.776409282 +0000
+++ /dev/fd/62 2020-08-24 17:16:58.776409282 +0000
@@ -6,18 +6,18 @@
00000050 0f 30 0d 06 03 55 04 07 0c 06 44 61 6c 6c 61 73 |.0...U....Dallas|
00000060 31 27 30 25 06 03 55 04 0a 0c 1e 54 65 78 61 73 |1'0%..U....Texas|
00000070 20 49 6e 73 74 72 75 6d 65 6e 74 73 20 49 6e 63 | Instruments Inc|
-00000080 84 8b 96 2c 0c 12 18 03 01 05 05 04 01 02 00 00 |...,............|
-00000090 07 06 44 45 20 01 0d 14 2a 01 00 32 05 24 30 48 |..DE ...*..2.$0H|
-000000a0 60 6c 30 14 01 00 00 0f ac 04 01 00 00 0f ac 04 |`l0.............|
-000000b0 01 00 00 0f ac 02 0c 00 2d 1a 6f 18 17 ff ff ff |........-.o.....|
+00000080 6f 72 70 6f 72 61 74 65 64 31 13 30 11 06 03 55 |orporated1.0...U|
+00000090 04 0b 0c 0a 50 72 6f 63 65 73 73 6f 72 73 31 13 |....Processors1.|
+000000a0 30 11 06 03 55 04 03 0c 0a 54 49 20 73 75 70 70 |0...U....TI supp|
+000000b0 6f 72 74 31 1d 30 1b 06 09 2a 86 48 86 f7 0d 01 |ort1.0...*.H....|
000000c0 09 01 16 0e 73 75 70 70 6f 72 74 40 74 69 2e 63 |....support@ti.c|
000000d0 6f 6d 30 1e 17 0d 32 30 30 37 32 32 31 31 30 30 |om0...2007221100|
000000e0 30 30 5a 17 0d 32 30 30 38 32 31 31 31 30 30 30 |00Z..20082111000|
000000f0 30 5a 30 81 9d 31 0b 30 09 06 03 55 04 06 13 02 |0Z0..1.0...U....|
-00000100 00 00 27 a4 00 00 42 43 5e 00 62 32 2f 00 b4 96 |..'...BC^.b2/...|
-00000110 24 44 0c 00 c6 00 43 0a 00 00 0b f0 43 a5 2a 01 |$D....C.....C.*.|
-00000120 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
-*
+00000100 55 53 31 0b 30 09 06 03 55 04 08 0c 02 54 58 31 |US1.0...U....TX1|
+00000110 0f 30 0d 06 03 55 04 07 0c 06 44 61 6c 6c 61 73 |.0...U....Dallas|
+00000120 31 27 30 25 06 03 55 04 0a 0c 1e 54 65 78 61 73 |1'0%..U....Texas|
+00000130 20 49 6e 73 74 72 75 6d 65 6e 74 73 20 49 6e 63 | Instruments Inc|
00000140 6f 72 70 6f 72 61 74 65 64 31 13 30 11 06 03 55 |orporated1.0...U|
00000150 04 0b 0c 0a 50 72 6f 63 65 73 73 6f 72 73 31 13 |....Processors1.|
00000160 30 11 06 03 55 04 03 0c 0a 54 49 20 73 75 70 70 |0...U....TI supp|

[...]

000017a0 02 8a e5 06 c8 8c e2 14 c2 8a e5 7c 01 00 ea ed |...........|....|
000017b0 1f 8f e2 66 02 00 ea 5b 45 72 72 6f 72 5d 20 52 |...f...[Error] R|
-000017c0 69 64 20 55 54 43 20 49 44 21 21 21 0a 00 00 5b |id UTC ID!!!...[|
-000017d0 45 72 72 6f 72 5d 20 49 6e 76 61 6c 69 64 20 50 |Error] Invalid P|
-000017e0 65 65 72 20 43 68 61 6e 6e 65 6c 20 4e 75 6d 62 |eer Channel Numb|
-000017f0 65 72 21 21 21 0a 00 41 73 73 65 72 74 69 6f 6e |er!!!..Assertion|
+000017c0 4d 20 41 6c 6c 6f 63 20 54 58 20 43 68 20 66 61 |M Alloc TX Ch fa|
+000017d0 69 6c 65 64 21 21 21 0a 00 00 00 73 72 63 2f 75 |iled!!!....src/u|
+000017e0 64 6d 61 5f 63 68 2e 63 00 00 00 75 74 63 49 6e |dma_ch.c...utcIn|
+000017f0 66 6f 20 21 3d 20 4e 55 4c 4c 5f 50 54 52 00 75 |fo != NULL_PTR.u|
00001800 74 63 49 64 20 3c 3d 20 55 44 4d 41 5f 4e 55 4d |tcId <= UDMA_NUM|
00001810 5f 55 54 43 5f 49 4e 53 54 41 4e 43 45 00 00 72 |_UTC_INSTANCE..r|

Jan

>
>>
>> What is the flash on the board?
>
> Le, could you answer that more precisely than I could?
>
> Thanks,
> Jan
>
>>
>>>
>>> with open("out2.bin", "wb") as out:
>>> with open("/dev/mtd0", "rb") as mtd:
>>> out.write(mtd.read(0x20000))
>>>
>>> (or "mtd_debug read") is fine.
>>>
>>> What could be the reason? Our DTBs and k3-am654-base-board.dtb had some
>>> deviations /wrt the ospi node, but aligning ours to the base board made
>>> no difference.
>>>
>>> Jan
>>>
>>> [1] https://github.com/siemens/linux/commits/jan/iot2050
>>>
>

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