On 12/01/2023 10:06, Wolfram Sang wrote:
> From: Cong Dang <cong.dang.xn@xxxxxxxxxxx>
>
> The dummy cycles value was wrongly calculated if dummy.buswidth > 1,
> which affects QSPI, OSPI, HyperFlash on various SoCs. We're lucky in
> Single SPI case since its dummy.buswidth equals to 1, so the result of
> the division is unchanged
>
> This issue can be reproduced using something like the following commands
> A. QSPI mode: Mount device with jffs2 format
> jffs2: CLEANMARKER node found at 0x00000004, not first node in block (0x00000000)
>
> B. QSPI mode: Write data to mtd10, where mtd10 is a parition on SPI Flash
> storage, defined properly in a device tree
>
> [Correct fragment, read from SPI Flash]
>
> root@v3x:~# echo "hello" > /dev/mtd10
> root@v3x:~# hexdump -C -n100 /dev/mtd10
> 00000000 68 65 6c 6c 6f 0a ff ff ff ff ff ff ff ff ff ff |hello...........|
> 00000010 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |................|
>
> [Incorrect read of the same fragment: see the difference at offsets 0-3]
>
> root@v3x:~# echo "hello" > /dev/mtd10
> root@v3x:~# hexdump -C -n100 /dev/mtd10
> 00000000 00 00 00 00 68 65 6c 6c 6f 0a ff ff ff ff ff ff |....hello.......|
> 00000010 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |................|
>
> As seen from the result, 4 NULL bytes were inserted before the test data.
> Wrong calculation in rpcif_prepare() led to miss of some dummy cycle. A
> division by bus width is redundant because it had been performed already
> in spi-rpc-if.c::rpcif_spi_mem_prepare()
>
> Fix this by removing the redundant division.
>
> Fixes: ca7d8b980b67 ("memory: add Renesas RPC-IF driver")
> Signed-off-by: Cong Dang <cong.dang.xn@xxxxxxxxxxx>
> Signed-off-by: Hai Pham <hai.pham.ud@xxxxxxxxxxx>
> Signed-off-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
> ---
>
> Sadly, I cannot test this patch myself because I don't have access to
> hardware which uses a buswidth > 1 for the dummy read. However, from
> code review, this patch makes sense. The division by buswidth is done
> twice, once in the SPI driver and once in the RPC core. It should stay
> only in the SPI driver.
Any tests or further reviews on this? If not, I'll pick it up in few days.
Best regards,
Krzysztof
