linux-kernel - Re: [RFC PATCH 4/7] mmc: sdhci: Add quirk to indicate broken POWER

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Message-ID: <45762ded-3c42-fefc-e6bb-2542d75c9c67@intel.com>
Date:   Tue, 15 Aug 2017 10:41:37 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Kishon Vijay Abraham I <kishon@...com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Tony Lindgren <tony@...mide.com>,
        Rob Herring <robh+dt@...nel.org>
Cc:     nsekhar@...com, linux-omap@...r.kernel.org,
        linux-mmc@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 4/7] mmc: sdhci: Add quirk to indicate broken
 POWER_CONTROL

On 07/08/17 19:01, Kishon Vijay Abraham I wrote:
> TI's implementation of sdhci controller used in DRA7 SoC's uses
> POWER_CONTROL register for configuring IO voltage and not
> for core voltage (vdd) which is it's intended use. Add a quirk
> to indicate broken POWER_CONTROL register.

A quirk isn't needed for this.  Use the ->set_power() callback instead.

> 
> Signed-off-by: Kishon Vijay Abraham I <kishon@...com>
> ---
>  drivers/mmc/host/sdhci.c | 6 ++++++
>  drivers/mmc/host/sdhci.h | 2 ++
>  2 files changed, 8 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index d5050ec42481..a7465a56e6b5 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -1419,6 +1419,9 @@ static void sdhci_set_power_reg(struct sdhci_host *host, unsigned char mode,
>  
>  	mmc_regulator_set_ocr(mmc, mmc->supply.vmmc, vdd);
>  
> +	if (host->quirks2 & SDHCI_QUIRK2_BROKEN_POWER_CONTROL)
> +		return;
> +
>  	if (mode != MMC_POWER_OFF)
>  		sdhci_writeb(host, SDHCI_POWER_ON, SDHCI_POWER_CONTROL);
>  	else
> @@ -1430,6 +1433,9 @@ void sdhci_set_power_noreg(struct sdhci_host *host, unsigned char mode,
>  {
>  	u8 pwr = 0;
>  
> +	if (host->quirks2 & SDHCI_QUIRK2_BROKEN_POWER_CONTROL)
> +		return;
> +
>  	if (mode != MMC_POWER_OFF) {
>  		switch (1 << vdd) {
>  		case MMC_VDD_165_195:
> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
> index 39c7a2723906..ba94cca7c892 100644
> --- a/drivers/mmc/host/sdhci.h
> +++ b/drivers/mmc/host/sdhci.h
> @@ -439,6 +439,8 @@ struct sdhci_host {
>  #define SDHCI_QUIRK2_NO_CRC_STRIPPING			(1<<16)
>  /* Controller has bad caps bits, but really supports DMA */
>  #define SDHCI_QUIRK2_FORCE_ADMA				(1<<17)
> +/* Controller uses POWER_CONTROL for managing IO voltage and not core voltage */
> +#define SDHCI_QUIRK2_BROKEN_POWER_CONTROL		(1<<18)
>  
>  	int irq;		/* Device IRQ */
>  	void __iomem *ioaddr;	/* Mapped address */
>