Re: [PATCH 3/4] mmc: dw_mmc: Add quirk for extended data read timeout

[Marten Lindahl <martenli@axis.com>]

On Thu, Dec 02, 2021 at 09:39:30AM +0100, Krzysztof Kozlowski wrote:

Hi Krzysztof!
Thanks for looking at this!

> On 01/12/2021 16:38, Mårten Lindahl wrote:
> > Current dw_mci driver supports a TMOUT register which consists of a 24
> > bit field (TMOUT[31:8]) for the DATA_TIMEOUT. The maximum value of this
> > field is 0xFFFFFF, which with a 200MHz clock will give a full DRTO of:
> > 
> > 0xFFFFFF / 200000000 => ~84 ms
> > 
> > However, the ARTPEC-8 SoC DWMMC IP version has a TMOUT register with an
> > extended DATA_TIMEOUT field, which supports longer timers for the DRTO.
> > In this version the DATA_TIMEOUT field is split into two, which with the
> > same 200MHz clock as above will allow a maximum timeout of:
> > 
> > ((TMOUT[10:8] -1) * 0xFFFFFF + TMOUT[31:11] * 8) / 200000000 => ~587 ms
> > 
> > Add a quirk to support this. The quirk is enabled for ARTPEC-8 SoCs.
> > 
> > Signed-off-by: Mårten Lindahl <marten.lindahl@axis.com>
> > ---
> >  drivers/mmc/host/dw_mmc-exynos.c |  5 +++++
> >  drivers/mmc/host/dw_mmc.c        | 33 ++++++++++++++++++++++++++++----
> >  drivers/mmc/host/dw_mmc.h        |  7 +++++++
> >  3 files changed, 41 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/mmc/host/dw_mmc-exynos.c b/drivers/mmc/host/dw_mmc-exynos.c
> > index cae7c94b5d6e..6ae9c0ec1282 100644
> > --- a/drivers/mmc/host/dw_mmc-exynos.c
> > +++ b/drivers/mmc/host/dw_mmc-exynos.c
> > @@ -127,6 +127,11 @@ static int dw_mci_exynos_priv_init(struct dw_mci *host)
> >  				DQS_CTRL_GET_RD_DELAY(priv->saved_strobe_ctrl);
> >  	}
> >  
> > +	if (priv->ctrl_type == DW_MCI_TYPE_ARTPEC8) {
> > +		/* Quirk needed for ARTPEC-8 SoCs */
> > +		host->quirks |= DW_MMC_QUIRK_EXTENDED_TMOUT;
> > +	}
> > +
> >  	host->bus_hz /= (priv->ciu_div + 1);
> >  
> >  	return 0;
> > diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> > index f2a14a434bef..45ea9fd97a6a 100644
> > --- a/drivers/mmc/host/dw_mmc.c
> > +++ b/drivers/mmc/host/dw_mmc.c
> > @@ -1289,6 +1289,7 @@ static void dw_mci_set_data_timeout(struct dw_mci *host,
> >  {
> >  	u32 clk_div, tmout;
> >  	u64 tmp;
> > +	unsigned int tmp2;
> >  
> >  	clk_div = (mci_readl(host, CLKDIV) & 0xFF) * 2;
> >  	if (clk_div == 0)
> > @@ -1301,10 +1302,28 @@ static void dw_mci_set_data_timeout(struct dw_mci *host,
> >  	tmout = 0xFF; /* Set maximum */
> >  
> >  	/* TMOUT[31:8] (DATA_TIMEOUT) */
> > -	if (!tmp || tmp > 0xFFFFFF)
> > -		tmout |= (0xFFFFFF << 8);
> > -	else
> > -		tmout |= (tmp & 0xFFFFFF) << 8;
> > +	if (host->quirks & DW_MMC_QUIRK_EXTENDED_TMOUT) {
> > +		/*
> > +		 * Extended HW timer (max = 0x6FFFFF2):
> > +		 * ((TMOUT[10:8] - 1) * 0xFFFFFF + TMOUT[31:11] * 8)
> > +		 */
> > +		if (!tmp || tmp > 0x6FFFFF2)
> > +			tmout |= (0xFFFFFF << 8);
> > +		else {
> > +			/* TMOUT[10:8] */
> > +			tmp2 = (((unsigned int)tmp / 0xFFFFFF) + 1) & 0x7;
> > +			tmout |= tmp2 << 8;
> > +
> > +			/* TMOUT[31:11] */
> > +			tmp = tmp - ((tmp2 - 1) * 0xFFFFFF);
> > +			tmout |= (tmp & 0xFFFFF8) << 8;
> > +		}
> > +	} else {
> > +		if (!tmp || tmp > 0xFFFFFF)
> > +			tmout |= (0xFFFFFF << 8);
> > +		else
> > +			tmout |= (tmp & 0xFFFFFF) << 8;
> > +	}
> >  
> >  	mci_writel(host, TMOUT, tmout);
> >  	dev_dbg(host->dev, "timeout_ns: %u => TMOUT[31:8]: 0x%#08x",
> > @@ -2005,9 +2024,15 @@ static void dw_mci_set_drto(struct dw_mci *host)
> >  	if (drto_div == 0)
> >  		drto_div = 1;
> >  
> > +	if (host->quirks & DW_MMC_QUIRK_EXTENDED_TMOUT)
> > +		drto_clks = (((drto_clks & 0x7) - 1) * 0xFFFFFF) +
> > +			((drto_clks & 0xFFFFF8));
> > +
> >  	drto_ms = DIV_ROUND_UP_ULL((u64)MSEC_PER_SEC * drto_clks * drto_div,
> >  				   host->bus_hz);
> >  
> > +	dev_dbg(host->dev, "drto_ms: %u\n", drto_ms);
> > +
> >  	/* add a bit spare time */
> >  	drto_ms += 10;
> >  
> > diff --git a/drivers/mmc/host/dw_mmc.h b/drivers/mmc/host/dw_mmc.h
> > index 771d5afa3136..071f4479f166 100644
> > --- a/drivers/mmc/host/dw_mmc.h
> > +++ b/drivers/mmc/host/dw_mmc.h
> > @@ -118,6 +118,7 @@ struct dw_mci_dma_slave {
> >   * @part_buf: Simple buffer for partial fifo reads/writes.
> >   * @push_data: Pointer to FIFO push function.
> >   * @pull_data: Pointer to FIFO pull function.
> > + * @quirks: Set of quirks that apply to specific versions of the IP.
> >   * @vqmmc_enabled: Status of vqmmc, should be true or false.
> >   * @irq_flags: The flags to be passed to request_irq.
> >   * @irq: The irq value to be passed to request_irq.
> > @@ -223,6 +224,9 @@ struct dw_mci {
> >  	void (*push_data)(struct dw_mci *host, void *buf, int cnt);
> >  	void (*pull_data)(struct dw_mci *host, void *buf, int cnt);
> >  
> > +	/* Workaround flags */
> 
> No need for this comment - you already described the field in kerneldoc.

Ok, will remove it.

> 
> > +	u32			quirks;
> > +
> >  	bool			vqmmc_enabled;
> >  	unsigned long		irq_flags; /* IRQ flags */
> >  	int			irq;
> > @@ -274,6 +278,9 @@ struct dw_mci_board {
> >  	struct dma_pdata *data;
> >  };
> >  
> > +/* Support for longer data read timeout */
> > +#define DW_MMC_QUIRK_EXTENDED_TMOUT	(1<<0)
> 
> BIT()

Will fix.

> 
> > +
> >  #define DW_MMC_240A		0x240a
> >  #define DW_MMC_280A		0x280a
> >  
> > 
> 

Kind regards
Mårten
> 
> Best regards,
> Krzysztof