[PATCH 1/2] mmc: core: enable CMD19 tuning for DDR50 mode

[Yang, York]

Hi, Carlo

	I don't think so. You may check the 9faac7b95, there are two changes in sd.c and sdhc.c.
	Surely the change in sdhc.c will not affect ASUS X205TA (bcm43341) since it is a SDIO device.
	Actually the calling sequence is this: mmc_sd_init_uhs_card() calls sdhci_execute_tuning(). In 9faac7b95, I enabled tuning for DDR50 in these two functions.
	If your function calling sequence is mmc_sdio_init_uhs_card()->sdhci_execute_tuning(), the tuning will not carried out, since you didn't enable tuning for DDR50 in mmc_sdio_init_uhs_card().
	Unless you call sdhci_execute_tuning directly, the tuning command may go through be sent out.

-----Original Message-----
From: carlo.caione at gmail.com [mailto:carlo.caione at gmail.com] On Behalf Of Carlo Caione
Sent: 2015年12月14日 17:14
To: Yang, York <weijuny at qti.qualcomm.com>
Cc: Carlo Caione <carlo at caione.org>; Ulf Hansson <ulf.hansson at linaro.org>; Barry Song <21cnbao at gmail.com>; linux-mmc <linux-mmc at vger.kernel.org>; DL-SHA-WorkGroupLinux <workgroup.linux at csr.com>; linux-arm-kernel at lists.infradead.org; Song, Barry <baohuas at qti.qualcomm.com>
Subject: Re: [PATCH 1/2] mmc: core: enable CMD19 tuning for DDR50 mode

On Mon, Dec 14, 2015 at 9:46 AM, Yang, York <weijuny at qti.qualcomm.com> wrote:
> Hi, Carlo
>         In 9faac7b95, tuning for DDR50 is enabled in mmc_sd_init_uhs_card(), so only SD card is affected.
>         This is based on the SD spec version 3.01.
>         mmc_sdio_init_uhs_card() is untouched. I don't know who add the code into mmc_sdio_init_uhs_card() and you may have a check on your side.

Hi Yang,
sorry for not being clear. Modifying mmc_sdio_init_uhs_card() was only a test I did to check whether that could fix the issue, but it didn't.

Right now the situation is:
- In the latest master with commit 9faac7b95 WiFi is broken on the ASUS X205TA (bcm43341)
- Reverting 9faac7b95 makes it working fine again

My conclusion is that issuing the CMD19 is basically breaking WiFi on this platform.

--
Carlo Caione