Re: [PATCH v4 2/3] staging: axis-fifo: Fix alignment of wait_event_interruptible arguments

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] The driver incorrectly uses register I/O accessors (iowrite32/ioread32) for FIFO stream data, corrupting the payload byte order on big-endian architectures.
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commit 2b61bbc0527fc4d755d68d7a70237195d89efad6
Author: Pramod Maurya <pramod.nexgen@gmail.com>

staging: axis-fifo: Fix alignment of wait_event_interruptible arguments

This commit resolves a checkpatch warning about argument alignment in
wait_event_interruptible(). It breaks the condition at the comparison
operator to keep the line under 80 columns.

> diff --git a/drivers/staging/axis-fifo/axis-fifo.c b/drivers/staging/axis-fifo/axis-fifo.c
> index 3aa2aa870ea91..1c34de020cf85 100644
> --- a/drivers/staging/axis-fifo/axis-fifo.c
> +++ b/drivers/staging/axis-fifo/axis-fifo.c
> @@ -246,7 +246,8 @@ static ssize_t axis_fifo_write(struct file *f, const char __user *buf,
>  		mutex_lock(&fifo->write_lock);
>  
>  		ret = wait_event_interruptible(fifo->write_queue,
> -			ioread32(fifo->base_addr + XLLF_TDFV_OFFSET) >= words_to_write);
> +					       ioread32(fifo->base_addr + XLLF_TDFV_OFFSET) >=
> +					       words_to_write);
>  		if (ret)
>  			goto end_unlock;
>  	}

This isn't a bug introduced by this commit, but while reviewing
axis_fifo_write() I noticed a potential endianness issue later in the
function:

	for (int i = 0; i < words_to_write; ++i)
		iowrite32(txbuf[i], fifo->base_addr + XLLF_TDFD_OFFSET);

Could this loop corrupt the payload byte order on big-endian architectures?

Stream data fifos must exclusively use stream accessors (such as writesl()
and readsl()) to preserve memory byte order without applying unwanted
byte-swapping.

The driver currently uses register I/O accessors to transfer data to and
from the fifos (XLLF_TDFD_OFFSET and XLLF_RDFD_OFFSET). On big-endian
systems, iowrite32() maps to writel(), which performs CPU-to-device
byteswapping.

Are there similar issues in axis_fifo_read() where ioread32() is used to
read from XLLF_RDFD_OFFSET?

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Sashiko AI review · https://sashiko.dev/#/patchset/20260515075736.172172-1-pramod.nexgen@gmail.com?part=2