From: Tom Rini <trini@konsulko.com>
To: u-boot@lists.denx.de
Subject: [U-Boot] [PATCH 5/6] mmc: move some SDHCI related options to Kconfig
Date: Wed, 7 Dec 2016 07:52:00 -0500 [thread overview]
Message-ID: <20161207125200.GQ4248@bill-the-cat> (raw)
In-Reply-To: <CAK7LNAQhsbLJ5xCghpy-sDGAQzh4PmqjDpdMmzoq3scccoFY+w@mail.gmail.com>
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_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 at pug:~/workspace/u-boot/configs$ git grep CONFIG_MMC_SDHCI=y | wc
> 54 54 2306
> masahiro at 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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next prev parent reply other threads:[~2016-12-07 12:52 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-04 13:23 [U-Boot] [PATCH 0/6] mmc: move some config options to Kconfig Masahiro Yamada
2016-12-04 13:23 ` [U-Boot] [PATCH 1/6] Sync defconfig files by savedefconfig Masahiro Yamada
2016-12-04 13:23 ` [U-Boot] [PATCH 2/6] mmc: complete the unfinished move of CONFIG_MMC Masahiro Yamada
2016-12-05 16:02 ` Tom Rini
2016-12-06 6:25 ` Masahiro Yamada
2016-12-06 13:03 ` Tom Rini
2016-12-07 1:45 ` Masahiro Yamada
2016-12-04 13:23 ` [U-Boot] [PATCH 3/6] mmc: make MMC driver entries dependent on MMC Masahiro Yamada
2016-12-05 19:11 ` Tom Rini
2016-12-04 13:23 ` [U-Boot] [PATCH 4/6] mmc: move CONFIG_SDHCI to Kconfig, renaming to CONFIG_MMC_SDHCI Masahiro Yamada
2016-12-05 16:04 ` Tom Rini
2016-12-04 13:23 ` [U-Boot] [PATCH 5/6] mmc: move some SDHCI related options to Kconfig Masahiro Yamada
2016-12-05 19:10 ` Tom Rini
2016-12-07 9:04 ` Masahiro Yamada
2016-12-07 9:22 ` Jaehoon Chung
2016-12-07 12:52 ` Tom Rini [this message]
2016-12-04 13:23 ` [U-Boot] [PATCH 6/6] mmc: move MMC_SDHCI_IO_ACCESSORS " Masahiro Yamada
2016-12-05 19:11 ` Tom Rini
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