Messages in this thread Patch in this message | | | Date | Fri, 26 Jun 2020 11:18:00 -0400 | From | Ralph Siemsen <> | Subject | Re: [PATCH 4.19 182/267] spi: dw: Return any value retrieved from the dma_transfer callback |
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Hi Serge, Pavel, Greg,
On Mon, Jun 22, 2020 at 11:51:21PM +0300, Serge Semin wrote: >Hello Pavel > >On Fri, Jun 19, 2020 at 11:07:19PM +0200, Pavel Machek wrote: > >> Mainline patch simply changes return value, but code is different in >> v4.19, and poll_transfer will now be avoided when dws->dma_mapped. Is >> that a problem? > >Actually no.) In that old 4.19 context it's even better to return straight away >no matter what value is returned by the dma_transfer() callback.
This patch changes the return dma_transfer return value from 0 to 1, however it was only done in spi-dw-mid.c func mid_spi_dma_transfer().
There is an identical function in spi-dw-mmio.c that needs the same treatment, otherwise access to the SPI device becomes erratic and even causes kernel to hang. Guess how I found this ;-)
So the following patch is needed as well, at least in 4.9 and 4.19, I did not check/test other versions. Mainline does not need this, since the code seems to have been refactored to avoid the duplication.
Regards, -Ralph
diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c index c563c2815093..99641c485288 100644 --- a/drivers/spi/spi-dw-mmio.c +++ b/drivers/spi/spi-dw-mmio.c @@ -358,7 +358,7 @@ static int mmio_spi_dma_transfer(struct dw_spi *dws, struct spi_transfer *xfer) dma_async_issue_pending(dws->txchan); } - return 0; + return 1; } static void mmio_spi_dma_stop(struct dw_spi *dws) -- 2.17.1
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