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

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Message-ID: <eff1b49e-e392-8887-b3a0-3caedc5b81cc@siemens.com>
Date:   Mon, 24 Aug 2020 19:20:51 +0200
From:   Jan Kiszka <jan.kiszka@...mens.com>
To:     Vignesh Raghavendra <vigneshr@...com>,
        Tudor Ambarus <tudor.ambarus@...rochip.com>,
        Mark Brown <broonie@...nel.org>,
        "Jin, Le (RC-CN DF FA R&D)" <le.jin@...mens.com>
Cc:     Boris Brezillon <bbrezillon@...nel.org>,
        Ramuthevar Vadivel Murugan 
        <vadivel.muruganx.ramuthevar@...ux.intel.com>,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-spi@...r.kernel.org, simon.k.r.goldschmidt@...il.com,
        dinguyen@...nel.org, marex@...x.de
Subject: Re: [RESEND PATCH v3 5/8] mtd: spi-nor: cadence-quadspi: Handle probe
 deferral while requesting DMA channel

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@...com>
>>>> Reviewed-by: Tudor Ambarus <tudor.ambarus@...rochip.com>
>>>> ---
>> [...]
>>>>
>>>>  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.$0H|
-000000a0  60 6c 30 14 01 00 00 0f  ac 04 01 00 00 0f ac 04  |`l0.............|
-000000b0  01 00 00 0f ac 02 0c 00  2d 1a 6f 18 17 ff ff ff  |........-.o.....|
+00000080  6f 72 70 6f 72 61 74 65  64 31 13 30 11 06 03 55  |orporated1.0...U|
+00000090  04 0b 0c 0a 50 72 6f 63  65 73 73 6f 72 73 31 13  |....Processors1.|
+000000a0  30 11 06 03 55 04 03 0c  0a 54 49 20 73 75 70 70  |0...U....TI supp|
+000000b0  6f 72 74 31 1d 30 1b 06  09 2a 86 48 86 f7 0d 01  |ort1.0...*.H....|
 000000c0  09 01 16 0e 73 75 70 70  6f 72 74 40 74 69 2e 63  |....support@...c|
 000000d0  6f 6d 30 1e 17 0d 32 30  30 37 32 32 31 31 30 30  |om0...2007221100|
 000000e0  30 30 5a 17 0d 32 30 30  38 32 31 31 31 30 30 30  |00Z..20082111000|
 000000f0  30 5a 30 81 9d 31 0b 30  09 06 03 55 04 06 13 02  |0Z0..1.0...U....|
-00000100  00 00 27 a4 00 00 42 43  5e 00 62 32 2f 00 b4 96  |..'...BC^.b2/...|
-00000110  24 44 0c 00 c6 00 43 0a  00 00 0b f0 43 a5 2a 01  |$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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