On Fri, Nov 06, 2015 at 04:59:29PM +0100, Ludovic Desroches wrote:
> When there is a vmmc regulator, only SD Bus Power is set to 1 in the
> Power Control Register. It means SD Bus Voltage Select field is set to 0
> that is a reserved value. The SD Host Controller specification says:
> 'SD Bus Power: Before setting this bit, the SD Host Driver shall set SD
> Bus Voltage Select.' and 'If the Host Driver selects an unsupported
> voltage in the SD B?us Voltage Select field, the Host Controller may
> ignore writes to SD Bus Power and keep its value at zero."
>
> Having an external regulator means the SD Bus Voltage Select is useless
> but if the Host Controller strictly follows the specification then we
> need to set a valid value.
Ulf,
What is your opinion about this patch?
If the 'no regulator found' message is turned in debug message, I can get
rid of my vmmc regulator but I really think that writing only
SDHCI_POWER_ON is opposite to the sdhci spec. I would say that not
setting the bus voltage is a quirk!
Regards
Ludovic
>
> Signed-off-by: Ludovic Desroches <ludovic.desroches@xxxxxxxxx>
> ---
> drivers/mmc/host/sdhci.c | 7 -------
> 1 file changed, 7 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index ac97b46..0cfd7b2 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -1278,13 +1278,6 @@ static void sdhci_set_power(struct sdhci_host *host, unsigned char mode,
> 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) {
> --
> 2.5.0
>
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