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

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Message-ID: <0ef75bd7-e7e6-a806-2c3f-35c7312c391d@samsung.com>
Date:   Wed, 10 May 2023 13:05:21 +0900
From:   Jaewon Kim <jaewon02.kim@...sung.com>
To:     Marek Szyprowski <m.szyprowski@...sung.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Andi Shyti <andi@...zian.org>, Mark Brown <broonie@...nel.org>,
        Alim Akhtar <alim.akhtar@...sung.com>
Cc:     linux-spi@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Chanho Park <chanho61.park@...sung.com>,
        Łukasz Stelmach <l.stelmach@...sung.com>
Subject: Re: [PATCH v3 3/3] spi: s3c64xx: support interrupt based pio mode

Hello Marek


On 23. 5. 9. 22:03, Marek Szyprowski wrote:
> 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@...sung.com>
> 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


Thanks for testing the various cases.

The problem occurred when DMA mode and IRQ mode were enabled at the same 
time.


In the above case, BUS_WIDTH register invaded.

Because, target length 496 were written to RX_RDY_LVL, but it exceeded 
6-bits.

Could you test with below code??? If the problem is solved, I will send 
a fix patch as soon as possible.

-----------------------------

diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
index 238db29fc93b..a72e11e965c3 100644
--- a/drivers/spi/spi-s3c64xx.c
+++ b/drivers/spi/spi-s3c64xx.c
@@ -782,7 +782,7 @@ static int s3c64xx_spi_transfer_one(struct 
spi_master *master,

         do {
                 /* transfer size is greater than 32, change to IRQ mode */
-               if (xfer->len > S3C64XX_SPI_POLLING_SIZE)
+               if (!use_dma && (xfer->len > S3C64XX_SPI_POLLING_SIZE))
                         use_irq = true;

                 if (use_irq) {

-----------------------------


Best regards

Jaewon Kim