Re: [RFC PATCH 6/8] misc: emif: add interrupt and temperature handling

[Aneesh V]

On Thursday 16 February 2012 04:11 PM, Santosh Shilimkar wrote:
> On Saturday 04 February 2012 05:46 PM, Aneesh V wrote:
> > Add an ISR for EMIF that:
> > 	1. reports details of access errors
> > 	2. takes action on thermal events
> >
> > On thermal events SDRAM timing parameters are
> > adjusted to ensure safe operation
> >
> > Also clear all interrupts on shut-down. Pending IRQs
> > may casue problems during warm-reset.
> Add some more details like MR4, EMIF polling frequency etc
> for better understanding.

Will do.



> > Signed-off-by: Aneesh V<aneesh@xxxxxx>
> > ---
> >   drivers/misc/emif.c |  209 ++++++++++++++++++++++++++++++++++++++++++++++++++-
> >   1 files changed, 207 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/misc/emif.c b/drivers/misc/emif.c
> > index 36ba6f4..5c2b0ae 100644
> > --- a/drivers/misc/emif.c
> > +++ b/drivers/misc/emif.c
> > @@ -500,6 +500,45 @@ static u32 get_pwr_mgmt_ctrl(u32 freq, struct emif_data *emif, u32 ip_rev)
> >   }
> >
> >   /*
> > + * Get the temperature level of the EMIF instance:
> > + * Reads the MR4 register of attached SDRAM parts to find out the temperature
> > + * level. If there are two parts attached(one on each CS), then the temperature
> > + * level for the EMIF instance is the higher of the two temperatures.
> > + */
> > +static void get_temperature_level(struct emif_data *emif)
> > +{
> > +	u32		temp, temperature_level;
> > +	unsigned long	irqs;
> > +	void __iomem	*base;
> > +
> > +	base = emif->base;
> > +
> > +	/* Read mode register 4 */
> > +	writel(DDR_MR4, base + EMIF_LPDDR2_MODE_REG_CONFIG);
> > +	temperature_level = readl(base + EMIF_LPDDR2_MODE_REG_DATA);
> > +	temperature_level = (temperature_level&  MR4_SDRAM_REF_RATE_MASK)>>
> > +				MR4_SDRAM_REF_RATE_SHIFT;
> > +
> > +	if (emif->plat_data->device_info->cs1_used) {
> > +		writel(DDR_MR4 | CS_MASK, base + EMIF_LPDDR2_MODE_REG_CONFIG);
> > +		temp = readl(base + EMIF_LPDDR2_MODE_REG_DATA);
> > +		temp = (temp&  MR4_SDRAM_REF_RATE_MASK)
> > +				>>  MR4_SDRAM_REF_RATE_SHIFT;
> > +		temperature_level = max(temp, temperature_level);
> > +	}
> > +
> > +	spin_lock_irqsave(&emif->lock, irqs);
> Add a line here.

Will do.

> > +	/* treat everything less than nominal(3) in MR4 as nominal */
> > +	if (unlikely(temperature_level<  SDRAM_TEMP_NOMINAL))
> > +		temperature_level = SDRAM_TEMP_NOMINAL;
> > +
> > +	/* if we get reserved value in MR4 persist with the existing value */
> > +	if (likely(temperature_level != SDRAM_TEMP_RESERVED_4))
> > +		emif->temperature_level = temperature_level;
> > +	spin_unlock_irqrestore(&emif->lock, irqs);
> > +}
> > +
>
> rest of the patch looks fine to me

Thanks,
Aneesh
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