RE: [PATCH v2 06/12] mmc: sd: add support for uhs bus speed mode selection

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Hi Subhash,


> -----Original Message-----
> From: subhashj@xxxxxxxxxxxxxx [mailto:subhashj@xxxxxxxxxxxxxx]
> Sent: Thursday, March 10, 2011 1:30 PM
> To: Nath, Arindam; cjb@xxxxxxxxxx
> Cc: zhangfei.gao@xxxxxxxxx; prakity@xxxxxxxxxxx; linux-
> mmc@xxxxxxxxxxxxxxx; Su, Henry; Lu, Aaron; anath.amd@xxxxxxxxx
> Subject: RE: [PATCH v2 06/12] mmc: sd: add support for uhs bus speed
> mode selection
> 
> 
> 
> > -----Original Message-----
> > From: Arindam Nath [mailto:anath.amd@xxxxxxxxx] On Behalf Of Arindam
> > Nath
> > Sent: Friday, March 04, 2011 5:03 PM
> > To: cjb@xxxxxxxxxx
> > Cc: zhangfei.gao@xxxxxxxxx; prakity@xxxxxxxxxxx;
> > subhashj@xxxxxxxxxxxxxx; linux-mmc@xxxxxxxxxxxxxxx; henry.su@xxxxxxx;
> > aaron.lu@xxxxxxx; anath.amd@xxxxxxxxx; Arindam Nath
> > Subject: [PATCH v2 06/12] mmc: sd: add support for uhs bus speed mode
> > selection
> >
> > This patch adds support for setting UHS-I bus speed mode during UHS-I
> > initialization procedure. Since both the host and card can support
> > more than one bus speed, we select the highest speed based on both of
> > their capabilities. First we set the bus speed mode for the card
> using
> > CMD6 mode 1, and then we program the host controller to support the
> > required speed mode. We also set High Speed Enable in case one of the
> > UHS-I modes is selected. Since MMC_TIMING_UHS_SDR25 is same as
> > MMC_TIMING_SD_HS, we don't need to set the SDHCI_CTRL_HISPD flag for
> > UHS SDR25 again. We also take care to reset SD clock before setting
> > UHS mode in the Host Control2 register, and then re-enable it as per
> > the Host Controller spec v3.00. We set the clock frequency for the
> > UHS-I mode selected.
> >
> > Signed-off-by: Arindam Nath <arindam.nath@xxxxxxx>
> > ---
> >  drivers/mmc/core/sd.c    |   91
> > ++++++++++++++++++++++++++++++++++++++++++++++
> >  drivers/mmc/host/sdhci.c |   32 +++++++++++++++-
> >  drivers/mmc/host/sdhci.h |    5 +++
> >  include/linux/mmc/card.h |   16 ++++++++
> >  include/linux/mmc/host.h |    4 ++
> >  5 files changed, 146 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
> > index f6a4fab..ec0d8e6 100644
> > --- a/drivers/mmc/core/sd.c
> > +++ b/drivers/mmc/core/sd.c
> > @@ -464,6 +464,92 @@ static int sd_select_driver_type(struct mmc_card
> > *card, u8 *status)
> >  	return 0;
> >  }
> >
> > +static int sd_set_bus_speed_mode(struct mmc_card *card, u8 *status)
> > +{
> > +	unsigned int bus_speed, timing;
> > +	int err;
> > +
> > +	/*
> > +	 * If the host doesn't support any of the UHS-I modes, fallback
> > on
> > +	 * default speed.
> > +	 */
> > +	if (!(card->host->caps & (MMC_CAP_UHS_SDR12 | MMC_CAP_UHS_SDR25 |
> > +	    MMC_CAP_UHS_SDR50 | MMC_CAP_UHS_SDR104 | MMC_CAP_UHS_DDR50)))
> > +		return 0;
> > +
> > +	if (card->host->caps & MMC_CAP_UHS_SDR104) {
> > +		if (card->sw_caps.uhs_bus_mode & SD_MODE_UHS_SDR104) {
> > +			bus_speed = UHS_SDR104_BUS_SPEED;
> > +			timing = MMC_TIMING_UHS_SDR104;
> > +			card->sw_caps.uhs_max_dtr = UHS_SDR104_MAX_DTR;
> > +		} else if (card->sw_caps.uhs_bus_mode & SD_MODE_UHS_SDR50)
> > {
> > +			bus_speed = UHS_SDR50_BUS_SPEED;
> > +			timing = MMC_TIMING_UHS_SDR50;
> > +			card->sw_caps.uhs_max_dtr = UHS_SDR50_MAX_DTR;
> > +		} else if (card->sw_caps.uhs_bus_mode & SD_MODE_UHS_DDR50)
> > {
> > +			bus_speed = UHS_DDR50_BUS_SPEED;
> > +			timing = MMC_TIMING_UHS_DDR50;
> > +			card->sw_caps.uhs_max_dtr = UHS_DDR50_MAX_DTR;
> > +		} else if (card->sw_caps.uhs_bus_mode & SD_MODE_UHS_SDR25)
> > {
> > +			bus_speed = UHS_SDR25_BUS_SPEED;
> > +			timing = MMC_TIMING_UHS_SDR25;
> > +			card->sw_caps.uhs_max_dtr = UHS_SDR25_MAX_DTR;
> > +		}
> > +	} else if (card->host->caps & MMC_CAP_UHS_SDR50) {
> > +		if ((card->sw_caps.uhs_bus_mode & SD_MODE_UHS_SDR104) ||
> > +		    (card->sw_caps.uhs_bus_mode & SD_MODE_UHS_SDR50)) {
> 
> You can combine both modes with "or": if (card->sw_caps.uhs_bus_mode &
> (SD_MODE_UHS_SDR104 | SD_MODE_UHS_SDR50)). This can be done for many of
> the
> below checks.

Thanks. Yes, it can be combined into a single check. Will do so.

> 
> > +			bus_speed = UHS_SDR50_BUS_SPEED;
> > +			timing = MMC_TIMING_UHS_SDR50;
> > +			card->sw_caps.uhs_max_dtr = UHS_SDR50_MAX_DTR;
> > +		} else if (card->sw_caps.uhs_bus_mode & SD_MODE_UHS_DDR50)
> > {
> > +			bus_speed = UHS_DDR50_BUS_SPEED;
> > +			timing = MMC_TIMING_UHS_DDR50;
> > +			card->sw_caps.uhs_max_dtr = UHS_DDR50_MAX_DTR;
> > +		} else if (card->sw_caps.uhs_bus_mode & SD_MODE_UHS_SDR25)
> > {
> > +			bus_speed = UHS_SDR25_BUS_SPEED;
> > +			timing = MMC_TIMING_UHS_SDR25;
> > +			card->sw_caps.uhs_max_dtr = UHS_SDR25_MAX_DTR;
> > +		}
> > +	} else if (card->host->caps & MMC_CAP_UHS_DDR50) {
> > +		if ((card->sw_caps.uhs_bus_mode & SD_MODE_UHS_SDR104) ||
> > +		    (card->sw_caps.uhs_bus_mode & SD_MODE_UHS_SDR50) ||
> > +		    (card->sw_caps.uhs_bus_mode & SD_MODE_UHS_DDR50)) {
> > +			bus_speed = UHS_DDR50_BUS_SPEED;
> > +			timing = MMC_TIMING_UHS_DDR50;
> > +			card->sw_caps.uhs_max_dtr = UHS_DDR50_MAX_DTR;
> > +		} else if (card->sw_caps.uhs_bus_mode & SD_MODE_UHS_SDR25)
> > {
> > +			bus_speed = UHS_SDR25_BUS_SPEED;
> > +			timing = MMC_TIMING_UHS_SDR25;
> > +			card->sw_caps.uhs_max_dtr = UHS_SDR25_MAX_DTR;
> > +		}
> > +	} else if (card->host->caps & MMC_CAP_UHS_SDR25) {
> > +		if ((card->sw_caps.uhs_bus_mode & SD_MODE_UHS_SDR104) ||
> > +		    (card->sw_caps.uhs_bus_mode & SD_MODE_UHS_SDR50) ||
> > +		    (card->sw_caps.uhs_bus_mode & SD_MODE_UHS_DDR50) ||
> > +		    (card->sw_caps.uhs_bus_mode & SD_MODE_UHS_SDR25)) {
> > +			bus_speed = UHS_SDR25_BUS_SPEED;
> > +			timing = MMC_TIMING_UHS_SDR25;
> > +			card->sw_caps.uhs_max_dtr = UHS_SDR25_MAX_DTR;
> > +		}
> > +	}
> > +
> > +	err = mmc_sd_switch(card, 1, 0, bus_speed, status);
> 
> For SDR12 mode, what will be the bus_speed?

Since for SDR12, the bus speed and clock freq are same as the default speed, I don't think we need to set them explicitly in case any of the above conditions fail. Please correct me if wrong.

> 
> 
> > +	if (err)
> > +		return err;
> > +
> > +	if ((status[16] & 0xF) != bus_speed)
> > +		printk(KERN_WARNING "%s: Problem setting bus speed
> > mode!\n",
> > +			mmc_hostname(card->host));
> > +	else {
> 
> For SDR12 mode, let's say you are setting the bus_speed =
> UHS_SDR12_BUS_SPEED (which is 0). Then for SDR12 mode there won't be a
> clock
> setting as you are checking if(buspeed). Is this what you want? How
> will you
> set the clock to 25 Mhz for SDR12 mode?

Please see the above comment.

Thanks,
Arindam

> 
> > +		if (bus_speed) {
> > +			mmc_set_timing(card->host, timing);
> > +			mmc_set_clock(card->host,
> card->sw_caps.uhs_max_dtr);
> > +		}
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> >  /*
> >   * UHS-I specific initialization procedure
> >   */
> > @@ -499,6 +585,11 @@ static int mmc_sd_init_uhs_card(struct mmc_card
> > *card)
> >
> >  	/* Set the driver strength for the card */
> >  	err = sd_select_driver_type(card, status);
> > +	if (err)
> > +		goto out;
> > +
> > +	/* Set bus speed mode of the card */
> > +	err = sd_set_bus_speed_mode(card, status);
> >
> >  out:
> >  	kfree(status);
> > diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> > index 5d3bb11..f127fa2 100644
> > --- a/drivers/mmc/host/sdhci.c
> > +++ b/drivers/mmc/host/sdhci.c
> > @@ -1278,7 +1278,13 @@ static void sdhci_set_ios(struct mmc_host
> *mmc,
> > struct mmc_ios *ios)
> >  		ctrl &= ~SDHCI_CTRL_HISPD;
> >
> >  	if (host->version >= SDHCI_SPEC_300) {
> > -		u16 ctrl_2;
> > +		u16 clk, ctrl_2;
> > +
> > +		/* In case of UHS-I modes, set High Speed Enable */
> > +		if ((ios->timing == MMC_TIMING_UHS_SDR50) ||
> > +		    (ios->timing == MMC_TIMING_UHS_SDR104) ||
> > +		    (ios->timing == MMC_TIMING_UHS_DDR50))
> > +			ctrl |= SDHCI_CTRL_HISPD;
> >
> >  		ctrl_2 = sdhci_readw(host, SDHCI_HOST_CONTROL2);
> >  		if (!(ctrl_2 & SDHCI_CTRL_PRESET_VAL_ENABLE)) {
> > @@ -1300,7 +1306,6 @@ static void sdhci_set_ios(struct mmc_host *mmc,
> > struct mmc_ios *ios)
> >  			 * need to reset SD Clock Enable before changing
> High
> >  			 * Speed Enable to avoid generating clock gliches.
> >  			 */
> > -			u16 clk;
> >
> >  			/* Reset SD Clock Enable */
> >  			clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> > @@ -1313,6 +1318,29 @@ static void sdhci_set_ios(struct mmc_host
> *mmc,
> > struct mmc_ios *ios)
> >  			clk |= SDHCI_CLOCK_CARD_EN;
> >  			sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
> >  		}
> > +
> > +		ctrl_2 = sdhci_readw(host, SDHCI_HOST_CONTROL2);
> > +
> > +		/* Select Bus Speed Mode for host */
> > +		if (ios->timing == MMC_TIMING_UHS_SDR25)
> > +			ctrl_2 |= SDHCI_CTRL_UHS_SDR25;
> > +		else if (ios->timing == MMC_TIMING_UHS_SDR50)
> > +			ctrl_2 |= SDHCI_CTRL_UHS_SDR50;
> > +		else if (ios->timing == MMC_TIMING_UHS_SDR104)
> > +			ctrl_2 |= SDHCI_CTRL_UHS_SDR104;
> > +		else if (ios->timing == MMC_TIMING_UHS_DDR50)
> > +			ctrl_2 |= SDHCI_CTRL_UHS_DDR50;
> > +
> > +		/* Reset SD Clock Enable */
> > +		clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> > +		clk &= ~SDHCI_CLOCK_CARD_EN;
> > +		sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
> > +
> > +		sdhci_writew(host, ctrl_2, SDHCI_HOST_CONTROL2);
> > +
> > +		/* Re-enable SD Clock */
> > +		clk |= SDHCI_CLOCK_CARD_EN;
> > +		sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
> >  	} else
> >  		sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL1);
> >
> > diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
> > index a407b5b..5bf244d 100644
> > --- a/drivers/mmc/host/sdhci.h
> > +++ b/drivers/mmc/host/sdhci.h
> > @@ -150,6 +150,11 @@
> >  #define SDHCI_ACMD12_ERR	0x3C
> >
> >  #define SDHCI_HOST_CONTROL2		0x3E
> > +#define  SDHCI_CTRL_UHS_SDR12		0x0000
> > +#define  SDHCI_CTRL_UHS_SDR25		0x0001
> > +#define  SDHCI_CTRL_UHS_SDR50		0x0002
> > +#define  SDHCI_CTRL_UHS_SDR104		0x0003
> > +#define  SDHCI_CTRL_UHS_DDR50		0x0004
> >  #define  SDHCI_CTRL_VDD_180		0x0008
> >  #define  SDHCI_CTRL_DRV_TYPE_B		0x0000
> >  #define  SDHCI_CTRL_DRV_TYPE_A		0x0010
> > diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
> > index 2d7f7a3..0b24c41 100644
> > --- a/include/linux/mmc/card.h
> > +++ b/include/linux/mmc/card.h
> > @@ -75,7 +75,23 @@ struct sd_ssr {
> >
> >  struct sd_switch_caps {
> >  	unsigned int		hs_max_dtr;
> > +	unsigned int		uhs_max_dtr;
> > +#define UHS_SDR104_MAX_DTR	208000000
> > +#define UHS_SDR50_MAX_DTR	100000000
> > +#define UHS_DDR50_MAX_DTR	50000000
> > +#define UHS_SDR25_MAX_DTR	50000000
> >  	unsigned int		uhs_bus_mode;
> > +#define UHS_SDR12_BUS_SPEED	0
> > +#define UHS_SDR25_BUS_SPEED	1
> > +#define UHS_SDR50_BUS_SPEED	2
> > +#define UHS_SDR104_BUS_SPEED	3
> > +#define UHS_DDR50_BUS_SPEED	4
> > +
> > +#define SD_MODE_UHS_SDR12	(1 << UHS_SDR12_BUS_SPEED)
> > +#define SD_MODE_UHS_SDR25	(1 << UHS_SDR25_BUS_SPEED)
> > +#define SD_MODE_UHS_SDR50	(1 << UHS_SDR50_BUS_SPEED)
> > +#define SD_MODE_UHS_SDR104	(1 << UHS_SDR104_BUS_SPEED)
> > +#define SD_MODE_UHS_DDR50	(1 << UHS_DDR50_BUS_SPEED)
> >  	unsigned int		uhs_drv_type;
> >  #define SD_DRIVER_TYPE_B	0x01
> >  #define SD_DRIVER_TYPE_A	0x02
> > diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> > index bc2121e..4dfff6d 100644
> > --- a/include/linux/mmc/host.h
> > +++ b/include/linux/mmc/host.h
> > @@ -50,6 +50,10 @@ struct mmc_ios {
> >  #define MMC_TIMING_LEGACY	0
> >  #define MMC_TIMING_MMC_HS	1
> >  #define MMC_TIMING_SD_HS	2
> > +#define MMC_TIMING_UHS_SDR25	MMC_TIMING_SD_HS
> > +#define MMC_TIMING_UHS_SDR50	3
> > +#define MMC_TIMING_UHS_SDR104	4
> > +#define MMC_TIMING_UHS_DDR50	5
> >
> >  	unsigned char	ddr;			/* dual data rate used */
> >
> > --
> > 1.7.1
> 
> 


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