mmc: renesas_sdhi_internal_dmac: limit DMA RX for old SoCs
Early revisions of certain SoCs cannot do multiple DMA RX streams in
parallel. To avoid data corruption, only allow one DMA RX channel and
fall back to PIO, if needed.
Signed-off-by: Wolfram Sang <wsa+renesas at sang-engineering.com>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh at renesas.com>
Tested-by: Nguyen Viet Dung <dung.nguyen.aj at renesas.com>
Reviewed-by: Simon Horman <horms+renesas at verge.net.au>
Cc: stable at vger.kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson at linaro.org>
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