Hi Przemyslaw,
On 08/26/2015 10:12 AM, Przemyslaw Marczak wrote:
Hi Humberto,
On 08/26/2015 03:40 PM, Humberto López León wrote:
Hi community,
thank you all for answering my questions.
On 08/26/2015 02:53 AM, Przemyslaw Marczak wrote:
Hi,
On 08/26/2015 08:23 AM, Jaehoon Chung wrote:
On 08/26/2015 11:26 AM, Simon Glass wrote:
+Samsung people
Hi,
On 25 August 2015 at 13:10, Humberto López León humberto@uclv.cu wrote:
Hi Simon, I'm working on implementing a driver for SD/MMC cards in the framework GenodeOS. I think you could help me with your experience in this type of implementation in the u-boot. The hardware platform on which the driver will work is a ODROID-x2 (exynos4412). I use the DWMMC contoller, but I'm not sure if this is the right controller to handle SD/MMC cards in Exynos4412 SoC. The SDHCI controller is most appropriate?
If you're using exynos4412 board, you can choose sdhci or dwmmc controller for eMMC, not SD/SDIO. And in my experiment, dwmmc controller is more appropriate than sdhci.(ex, performance)
It depends which mmc channel is used. In Exynos4412, there are 5 channels, but some channel configurations shares GPIO pins:
- MMC0 - sdhci
- MMC1 - sdhci, or MMC0 8-bit
- MMC2 - sdhci - Odroid SD card, 4-bit mode
- MMC3 - sdhci - or MMC2 8-bit
- MMC4 - dwmmc, uses MMC0 pins for 4-bit, and MMC0-1 for 8-bit mode
Odroid is using MMC2(sdhci) and MMC0/4(sdhci or dwmmc).
So for eMMC cards you can use the dwmmc, and as Jaehoon wrote it is recommended for the better performance, but for SD card you must use sdhci controller.
This information is valuable to me, but now I would help if you tell me where I can find the code of SDHCI controller for the SD card of Exynos4412 in U-boat 2015.04-rc2 for a implementationtation reference. I was reviewing the file exynos_dw_mmc.c as reference of DWMMC driver, but now I have no idea what the file where the SDHCI driver for the exynos4412 is implemented.
Thank you very much for your collaboration.
Please check those files:
- drivers/mmc/s5p_sdhci.c
- drivers/mmc/sdhci.c
But, isn't the kernel a better reference for you?
Thanks for your time to answer my questions. I have reviewed the implementation of SDHCI controller in the Linux kernel for Odroid (https://github.com/hardkernel/linux/blob/odroid-3.0.y/), but have not been able to identify the specific implementation that is used for handling of SD cards in exynos4412. You know in what file this controller is implemented? I think the file should be drivers/mmc/host/sdhci-s3c.c (https://github.com/hardkernel/linux/blob/odroid-3.0.y/drivers/mmc/host/sdhci...) but I'm not sure. What do you think?
Thanks again.
Humberto