On Wednesday, June 03, 2015 at 11:26:41 PM, Michal Suchanek wrote: > On sunxi the SPI controller currently does not have DMA support and fails > any transfer larger than 63 bytes. > > On Exynos the pl330 DMA controller fails any transfer larger than 64kb > when using slower speed like 40MHz and any transfer larger than 128bytes > when running at 133MHz. This smells more like some corruption of the data on the bus or something even more obscure. > The best thing is that in both cases the controller can just lock up and > never finish potentially leaving the hardware in unusable state. > > So it is required that the m25p80 driver actively prevents doing > transfers that are too large for the current driver state on a > particular piece of hardware. > > Signed-off-by: Michal Suchanek <hramrach@xxxxxxxxx> > > -- > > Update commit message and documentation text. > --- > .../devicetree/bindings/mtd/jedec,spi-nor.txt | 6 ++++++ > drivers/mtd/devices/m25p80.c | 24 > ++++++++++++++++++++-- 2 files changed, 28 insertions(+), 2 deletions(-) > > diff --git a/Documentation/devicetree/bindings/mtd/jedec,spi-nor.txt > b/Documentation/devicetree/bindings/mtd/jedec,spi-nor.txt index > 2bee681..4e63ae8 100644 > --- a/Documentation/devicetree/bindings/mtd/jedec,spi-nor.txt > +++ b/Documentation/devicetree/bindings/mtd/jedec,spi-nor.txt > @@ -19,6 +19,12 @@ Optional properties: > all chips and support for it can not be detected at > runtime. Refer to your chips' datasheet to check if this is supported by > your chip. > +- linux,max_tx_len : With some SPI controller drivers possible transfer > size is + limited. This may be hardware or driver bug. > + Transfer data in chunks no larger than this value. + > Using this option may severely degrade performance and > + possibly flash memory life when max_tx_len is > smaller than + flash page size (typically 256 bytes) Will we need similar patch for all other SPI slave drivers, like SPI NAND ? Best regards, Marek Vasut -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
