On Wed, Dec 07, 2016 at 06:04:21PM +0900, Masahiro Yamada wrote: > Hi Tom > > 2016-12-06 4:10 GMT+09:00 Tom Rini <tr...@konsulko.com>: > > On Sun, Dec 04, 2016 at 10:23:13PM +0900, Masahiro Yamada wrote: > > > >> While I moved the options, I also renamed them so that they are all > >> prefixed with MMC_SDHCI_. > > [snip] > >> diff --git a/drivers/mmc/Kconfig b/drivers/mmc/Kconfig > >> index 8e9fa2d..4785d71 100644 > >> --- a/drivers/mmc/Kconfig > >> +++ b/drivers/mmc/Kconfig > >> @@ -132,6 +132,68 @@ config MMC_SDHCI > >> > >> If unsure, say N. > >> > >> +config MMC_SDHCI_SDMA > >> + bool "Support SDHCI SDMA" > >> + depends on MMC_SDHCI > >> + help > >> + This enables support for the SDMA (Single Operation DMA) defined > >> + in the SD Host Controller Standard Specification Version 1.00 . > > > > I think this should be a default y. > > No. > > After my conversion, > > masahiro@pug:~/workspace/u-boot/configs$ git grep CONFIG_MMC_SDHCI=y | wc > 54 54 2306 > masahiro@pug:~/workspace/u-boot/configs$ git grep CONFIG_MMC_SDHCI_SDMA=y | wc > 21 21 995 > > > So, SDMA is disabled for more than half of boards with SDHCI driver. > > > I know one more reason that we should not enable option by default. > > SDMA is so old that it only supports 32 bit physical address. > > U-Boot uses the tail of memory area as work RAM. > > If SDMA is enabled on 64bit boards, MMC does not work > because the controller cannot read EXT-CSD data. > > Given increasing ARMv8 boards, > we want to use ADMA(2), but it is not supported in U-Boot. > > Anyway, I believe SDMA does not deserve default.
OK, thanks, agreed! -- Tom
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