Re: [PATCH v3 3/3] spi: s3c64xx: support interrupt based pio mode

[Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>]

On 02.05.2023 08:28, Jaewon Kim wrote:
> Support interrupt based pio mode to optimize cpu usage.
> When transmitting data size is larget than 32 bytes, operates with
> interrupt based pio mode.
>
> By using the FIFORDY INT, an interrupt can be triggered when
> the desired size of data has been received. Using this, we can support
> interrupt based pio mode.
>
> Signed-off-by: Jaewon Kim <jaewon02.kim@xxxxxxxxxxx>

This patch landed recently in linux-next as commit 1ee806718d5e ("spi: 
s3c64xx: support interrupt based pio mode"). Unfortunately it breaks 
ethernet chip operation on Exynos3250 based Artik5 Development board. I 
see the flood of the following messages:

[   36.097739] ax88796c spi0.0: I/O Error: rx-1 tx-0 rx-f tx-p len-496 
dma-1 res-(-5)
[   36.100877] ax88796c spi0.0: RX residue: 248
[   36.101383] ax88796c spi0.0: SPI transfer failed: -5
[   36.101939] spi_master spi0: failed to transfer one message from queue
[   36.102439] ax88796c spi0.0: axspi_read_rxq() failed: ret = -5
[   36.107830] s3c64xx-spi 13920000.spi: Failed to get RX DMA channel
[   36.148875] ax88796c spi0.0: I/O Error: rx-0 tx-1 rx-p tx-f len-4 
dma-0 res-(-5)
[   36.149517] ax88796c spi0.0: SPI transfer failed: -5
[   36.150053] spi_master spi0: failed to transfer one message from queue
[   36.150562] ax88796c spi0.0: axspi_read_reg() failed: ret = -5
[   36.152175] s3c64xx-spi 13920000.spi: Failed to get RX DMA channel
[   36.191651] ax88796c spi0.0: I/O Error: rx-0 tx-1 rx-p tx-f len-4 
dma-0 res-(-5)
[   36.192268] ax88796c spi0.0: SPI transfer failed: -5

...

I didn't analyze the details, but imho it looks like some kind of 
mishandling of the corner case or switching between PIO and DMA mode. I 
will check the details later.


Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland