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 trini@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_SDHCIhelpThis enables support for the SDMA (Single Operation DMA) definedin 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!