Dear Ulf, Ludovic,
Sorry for top post. I'm under webmail for I have no proper email client now.
OOPS, I should ask mmc maintainers and experts for help early. I spent two
days to debug the issue then found the two problematic commits.
PS: It seems other sdhci-pxav3 users never complained, it's a bit strange ;)
Thanks for reviewing this patch,
Jisheng
________________________________________
From: Ulf Hansson
Sent: Friday, December 11, 2015 22:48
To: Jisheng Zhang; Ludovic Desroches
Cc: linux-mmc; linux-kernel@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Subject: Re: [PATCH v2] mmc: sdhci: restore behavior when setting VDD via external regulator
+ Ludovic (We had some discussions around this code recently as well)
On 11 December 2015 at 14:36, Jisheng Zhang <jszhang@xxxxxxxxxxx> wrote:
> After commit 52221610dd84 ("mmc: sdhci: Improve external VDD regulator
> support"), for the VDD is supplied via external regulators, we ignore
> the code to convert a VDD voltage request into one of the standard
> SDHCI voltage levels, then program it in the SDHCI_POWER_CONTROL. This
> brings two issues:
>
> 1. SDHCI_QUIRK2_CARD_ON_NEEDS_BUS_ON quirk isn't handled properly any
> more.
>
> 2. What's more, once SDHCI_POWER_ON bit is set, some controllers such
> as the sdhci-pxav3 used in marvell berlin SoCs require the voltage
> levels programming in the SDHCI_POWER_CONTROL register, even the VDD
> is supplied by external regulator. So the host in marvell berlin SoCs
> still works fine after the commit. However, commit 3cbc6123a93d ("mmc:
> sdhci: Set SDHCI_POWER_ON with external vmmc") sets the SDHCI_POWER_ON
> bit, this would make the host in marvell berlin SoCs won't work any
> more with external vmmc.
>
> This patch restores the behavior when setting VDD through external
> regulator by moving the call of mmc_regulator_set_ocr() to the end
> of sdhci_set_power() function.
>
> After this patch, the sdcard on Marvell Berlin SoC boards work again.
>
> Signed-off-by: Jisheng Zhang <jszhang@xxxxxxxxxxx>
> Fixes: 52221610dd84 ("mmc: sdhci: Improve external VDD ...")
> ---
> Since v1:
> - add more details about why the sdhci-pxav3 used in marvell berlin
> SoCs need this patch.
>
> drivers/mmc/host/sdhci.c | 19 ++++++-------------
> 1 file changed, 6 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index b48565e..616aa90 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -1274,19 +1274,6 @@ static void sdhci_set_power(struct sdhci_host *host, unsigned char mode,
> struct mmc_host *mmc = host->mmc;
> u8 pwr = 0;
>
> - if (!IS_ERR(mmc->supply.vmmc)) {
> - spin_unlock_irq(&host->lock);
> - mmc_regulator_set_ocr(mmc, mmc->supply.vmmc, vdd);
> - spin_lock_irq(&host->lock);
> -
> - if (mode != MMC_POWER_OFF)
> - sdhci_writeb(host, SDHCI_POWER_ON, SDHCI_POWER_CONTROL);
> - else
> - sdhci_writeb(host, 0, SDHCI_POWER_CONTROL);
> -
> - return;
> - }
> -
> if (mode != MMC_POWER_OFF) {
> switch (1 << vdd) {
> case MMC_VDD_165_195:
> @@ -1345,6 +1332,12 @@ static void sdhci_set_power(struct sdhci_host *host, unsigned char mode,
> if (host->quirks & SDHCI_QUIRK_DELAY_AFTER_POWER)
> mdelay(10);
> }
> +
> + if (!IS_ERR(mmc->supply.vmmc)) {
> + spin_unlock_irq(&host->lock);
> + mmc_regulator_set_ocr(mmc, mmc->supply.vmmc, vdd);
> + spin_lock_irq(&host->lock);
> + }
> }
>
> /*****************************************************************************\
> --
> 2.6.3
>
My concern with this patch is that it might fix the problem for your
SDHCI variant, but will break it for others.
I guess we can give it try, unless or until someone reports a problem.
Although, I would like to get Ludovic's input on this change, before I
decide to do anything.
Kind regards
Uffe
--
To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
