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spi: atmel: introduce probe deferring

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Return probe defer if requesting a dma channel without a dma controller
probed.

Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Ludovic Desroches 2014-11-14 17:12:54 +01:00 committed by Mark Brown
parent 7758e39069
commit 5e9af37e46
1 changed files with 16 additions and 4 deletions
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20
drivers/spi/spi-atmel.c
View file

@ -427,14 +427,23 @@ static int atmel_spi_configure_dma(struct atmel_spi *as)
dma_cap_zero(mask);
dma_cap_set(DMA_SLAVE, mask);
as->dma.chan_tx = dma_request_slave_channel(dev, "tx");
if (!as->dma.chan_tx) {
as->dma.chan_tx = dma_request_slave_channel_reason(dev, "tx");
if (IS_ERR(as->dma.chan_tx)) {
err = PTR_ERR(as->dma.chan_tx);
if (err == -EPROBE_DEFER) {
dev_warn(dev, "no DMA channel available at the moment\n");
return err;
}
dev_err(dev,
"DMA TX channel not available, SPI unable to use DMA\n");
err = -EBUSY;
goto error;
}
/*
* No reason to check EPROBE_DEFER here since we have already requested
* tx channel. If it fails here, it's for another reason.
*/
as->dma.chan_rx = dma_request_slave_channel(dev, "rx");
if (!as->dma.chan_rx) {
@ -456,7 +465,7 @@ static int atmel_spi_configure_dma(struct atmel_spi *as)
error:
if (as->dma.chan_rx)
dma_release_channel(as->dma.chan_rx);
if (as->dma.chan_tx)
if (!IS_ERR(as->dma.chan_tx))
dma_release_channel(as->dma.chan_tx);
return err;
}
@ -1328,8 +1337,11 @@ static int atmel_spi_probe(struct platform_device *pdev)
as->use_dma = false;
as->use_pdc = false;
if (as->caps.has_dma_support) {
if (atmel_spi_configure_dma(as) == 0)
ret = atmel_spi_configure_dma(as);
if (ret == 0)
as->use_dma = true;
else if (ret == -EPROBE_DEFER)
return ret;
} else {
as->use_pdc = true;
}