[U-Boot] [PATCH 0/3] samsung: Add mmc controller to use dw mmc

[Jaehoon Chung]

On 03/05/2014 06:21 PM, Lukasz Majewski wrote:
> Hi Beomho,
> 
>> This patch set for use dw mmc controller.
>> First, add dw mmc controller initialization.
>> And then, change exynos4 mmc gpio configuration.
>> Additionally, I have removed exynos4x12_set_mmc_clk function.
>> Because samsung_get_base_clock() (exynos4x12/ exynos4) return same
>> value.
> 
> Thank you for supporting the DW_MMC on Trats2.
> 
> I've got following comments:
> 
> 1. Piotr Wilczek (added to CC) is moving the Trats/Trats2 board to
> support configuration via device tree. From device tree it is easier to
> seamlessly enable support for DW_MMC (SDMMC4 controller) - at least we
> would avoid adding new #ifdefs. The way to enable it is almost
> identical to Exynos5250 (board "snow").
> 
> Now the v4 has been sent, so please look (and probably rebase your work)
> on them:
> 
> "[PATCH V4 00/12] Exynos4: add support for device tree"
> http://article.gmane.org/gmane.comp.boot-loaders.u-boot/181576/match=exynos4+add+support+device+tree
Ok. It will be change to use the dt file.

> 
> 
> 2. We did some rough tests for the DW_MMC implementation on Trats2 (with
> clock phase settings similar to the one in the kernel) and it turned
> out that SDHCI is faster. 
> 
> Two possible explanations:
> - DDR is not supported by memory embedded on Trats2
> - We did something wrong, so as a result the DDR mode for
>   DW_MMC/eMMC memory was not working properly.
DDR mode didn't implement at u-boot. It need to update code for DDR mode.
If you want to use DDR mode, then i will implement it.

> 
> However, I still believe, that DW_MMC with properly enabled DDR could
> outperform SDHCI. 

Right, If DW-mmc is used with DDR mode, then it's more better than SDHCI.
there is no reason that we didn't use the dw-mmc controller at trats2 board.

> 
> Why this speedup is important?
> 
> We struggle to reduce time needed for flashing large images (like
> rootfs - e.g. 400 MiB in size).
> 
> Any help is more than welcome :-).
> 
> 
> 3. u-boot general advice:
> 
> When you alter things related to a particular board (like
> trats2 in this case) it is welcome to add the board's maintainer to CC.
> You can find them at boards.cfg.
Maybe, need to add Samsung-SoC maintainer, and base on SoC repository.

Best Regards,
Jaehoon Chung
> 
>>
>> This patch set is tested on Trats2 board.
>>
>> Beomho Seo (3):
>>   board: samsung: trats2: Add DW MMC controller initialization
>>   arm: exynos: pinmux: Add sdmmc4 gpio confifuration
>>   arm: exynos: clock: Remove exynos4x12_set_mmc_clk function
>>
>>  arch/arm/cpu/armv7/exynos/clock.c  |   29
>> +---------------------------- arch/arm/cpu/armv7/exynos/pinmux.c |
>> 20 +++++++++++++++----- board/samsung/trats2/trats2.c      |   31
>> +++++++++++++++++++++---------- 3 files changed, 37 insertions(+), 43
>> deletions(-)
> 
> 
>