Re: [PATCH] mmc: omap_hsmmc: Add small delay after enabling power

Ulf Hansson
2014-09-11T14:15:41Z

On 11 September 2014 16:11, Stefan Roese <sr@denx.de> wrote:
> From: Thorsten Einsbein <thorsten.eisbein@head-acoustics.de>
>
> On the TAO3530 (OMAP3530 based) we noticed that some SD cards are not
> detected reliably upon bootup (timeout). Especially the SanDisk Ultra
> 8GiB seems to be problematic here. The SanDisk Extreme also has this
> problem on this platform, but not that often. A Samsung 8 GiB type 6
> doesn't show this problem at all.
>
> This patch now adds a short delay after enabling the power on the slot.
> With this delay all cards are detected reliably.

Is this delay related to regulator ramp up/down time? Then I think it
maybe should be a part of the regulator code/DT.

Kind regards
Uffe

>
> Signed-off-by: Thorsten Einsbein <thorsten.eisbein@head-acoustics.de>
> Signed-off-by: Stefan Roese <sr@denx.de>
> Cc: Ulf Hansson <ulf.hansson@linaro.org>
> Cc: Balaji T K <balajitk@ti.com>
> ---
> drivers/mmc/host/omap_hsmmc.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
> index 9656726..62ff0a7 100644
> --- a/drivers/mmc/host/omap_hsmmc.c
> +++ b/drivers/mmc/host/omap_hsmmc.c
> @@ -335,6 +335,10 @@ static int omap_hsmmc_set_power(struct device *dev, int slot, int power_on,
> ret = mmc_regulator_set_ocr(host->mmc,
> host->vcc, 0);
> }
> +
> + dev_dbg(host->dev, "omap_hsmmc_set_power: wait a little (slot %d)\n",
> + slot);
> + msleep(5);
> } else {
> /* Shut down the rail */
> if (host->vcc_aux)
> --
> 2.1.0
>