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samsung: Add mmc controller to use dw mmc

Lukasz Majewski u-boot 1 version New

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

Hi Beomho,

Quoted 6 lines

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

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.

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

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.

Quoted 13 lines

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(-)

Signature · 5 lines
Best regards,

Lukasz Majewski

Samsung R&D Institute Poland (SRPOL) | Linux Platform Group

Read the cover letter in its thread