samsung: Add mmc controller to use dw mmc
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Cover letter [U-Boot] [PATCH 0/3] samsung: Add mmc controller to use dw mmc
Hi Jaehoon,
Quoted 20 lines · Lukasz Majewski
Quoted 19 lines
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 removedexynos4x12_set_mmc_clkfunction. Becausesamsung_get_base_clock()(exynos4x12/ exynos4) return same value.Thank you for supporting the
DW_MMCon 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").
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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+treeOk. It will be change to use the dt file.
That would be great. With DT support DW_MMC is even easier to enable.
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2. We did some rough tests for the
DW_MMCimplementation on Trats2 (with clock phase settings similar to the one in the kernel) and it turned out that SDHCI is faster.
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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.
Since SDHCI doesn't support DDR, with DW_MMC and DDR enabled, we shall (theoretically at least) observe substantial data transmission speed up.
Quoted 1 line
If you want to use DDR mode, then i will implement it.
That would be great :-).
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However, I still believe, that
DW_MMCwith properly enabled DDR could outperform SDHCI.Right, If DW-mmc is used with DDR mode, then it's more better than SDHCI.
I agree here.
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there is no reason that we didn't use the dw-mmc controller at trats2 board.
If DW_MMC+DDR turns out to be faster than SDHCI, then we will use it.
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Why this speedup is important?
We struggle to reduce time needed for flashing large images (like rootfs - e.g. 400 MiB in size).
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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 ChungQuoted 17 lines
Quoted 14 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: Removeexynos4x12_set_mmc_clkfunctionarch/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