Re: [PATCH v3 06/12] spi: spi-fsl-dspi: Replace interruptible wait queue with a simple completion

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Am 2020-03-16 17:23, schrieb Vladimir Oltean:
On Mon, 16 Mar 2020 at 15:25, Michael Walle <michael@xxxxxxxx> wrote:

Am 2020-03-16 14:00, schrieb Vladimir Oltean:
> On Mon, 16 Mar 2020 at 14:49, Mark Brown <broonie@xxxxxxxxxx> wrote:
>>
>> On Mon, Mar 16, 2020 at 02:29:09PM +0200, Vladimir Oltean wrote:
>>
>> > Correct, the real problem is that I forgot to add a Fixes: tag for
>> > patch 5. I'll do that now.
>>
>> OK.  The series otherwise looked fine but I'll wait for testing.
>> Michael, if there's issues remaining it might be good to get some
>> Tested-bys for the patches prior to whatever's broken so we can get
>> those fixes in (but obviously verifying that is work so only if you
>> have time).

I'm just about to test it. While my former "cat /dev/mtdN > /dev/null"
is working. I had the impression that it was slower, so I tried to test
it with dd now and a known chunk size.. only to find out that it is
still not working:

# dmesg|grep spi
[    1.894891] spi-nor spi1.0: w25q128fw (16384 Kbytes)
..
# time cat /dev/mtd0 > /dev/null
real    0m 30.73s
user    0m 0.00s
sys     0m 1.02s
# dd if=/dev/mtd0 of=/dev/null bs=64
262144+0 records in
262144+0 records out
# dd if=/dev/mtd0 of=/dev/null bs=64
262144+0 records in
262144+0 records out
# dd if=/dev/mtd0 of=/dev/null bs=64
dd: /dev/mtd0: Input/output error

I don't really have a SPI flash connected to DSPI on any LS1028A board.

I'm already debugging it again.

Is this DMA or XSPI mode?

XSPI mode. DMA mode looked good for now.


I also wanted to test how it behaves if there are multiple processes
access the /dev/mtdN device. I haven't found the time to dig into
the call chain if see if there is any locking. Because what happens
if transfer_one_message() is called twice at the same time from two
different processes?


There is a mutex on the SPI bus, and therefore all variants of the
.transfer() call are operating under this lock protection, which
simplifies things quite a bit.

Ok, thanks.

-michael

>
> This time I verified with a protocol analyzer all transfer lengths
> from 1 all the way to 256, with this script:
>
> #!/bin/bash
>
> buf=''
>
> for i in $(seq 0 255); do
> »       buf="${buf}\x$(printf '%02x' ${i})"
> »       spidev_test --device /dev/spidev2.0 --bpw 8 --cpha --speed
> 5000000 -p "${buf}"
> done
>
> It looked fine as far as I could tell, and also the problems
> surrounding Ctrl-C are no longer present. Nonetheless it would be good
> if Michael could confirm, but I know that he's very busy too so it's
> understandable if he can no longer spend time on this.

I'm working on it ;)

-michael

Thanks,
-Vladimir



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