Re: [PATCH 4/5] spi: zynqmp-gqspi: Allow interrupting operations

[Miquel Raynal <miquel.raynal@bootlin.com>]

Hello Sean,

On 16/01/2025 at 17:55:20 -05, Sean Anderson <sean.anderson@linux.dev> wrote:

> Some operations (such as reading several megabytes of data from a flash)
> can take several seconds or more. Users may want to cancel such
> operations. Allow them to do so now that we have a way to recover.

I fully agree with the observation, I tried myself interrupting too long
transfers with another spi controller:

e0205d6203c2c ("spi: atmel: Prevent false timeouts on long transfers")

But there were issues reported, so we limited the signals to SIGKILLs:

1ca2761a77349 ("spi: atmel: Do not cancel a transfer upon any signal")

But jffs2 plays with sigkills, so for spi memories it does not work
well, we had to revert:

890188d2d7e4a ("spi: atmel: Prevent spi transfers from being killed")

Same thing was also observed on Zynq7000:

26cfc0dbe43aa ("spi: spi-zynq-qspi: use wait_for_completion_timeout to make zynq_qspi_exec_mem_op not interruptible")

I would however hint to use a specific helper for deriving your timeouts
if you play with spi memories, because it is interesting to adapt the
values nevertheless:

d8e4ebf870187 ("spi: Create a helper to derive adaptive timeouts")

Thanks,
Miquèl