[U-Boot] [PATCH] mmc:sdhci:fix: Change default interrupts enabled at SDHCI initialization

[Lukasz Majewski]

Dear All,

I'd like to kindly ask for any feedback on this patch.

It is now more than month on the u-boot mailing list...


> Dear All,
> 
> Any feedback about this patch?
> 
> It has been on the list for quite long time.....
> 
> 
> > Dear All,
> > 
> > Any feedback about this patch?
> > 
> > > This patch changes sdhci_init()'s behavior to NOT enable all
> > > interrupt sources by default. Moreover interrupt signaling has
> > > been disabled.
> > > 
> > > This patch do not enable interrupts which aren't served in u-boot
> > > (they are defined at sdhci.h but NOT used elsewhere):
> > > - SDHCI_INT_CARD_INSERT, SDHCI_INT_CARD_REMOVE, SDHCI_BUS_POWER,
> > >   SDHCI_INT_CARD_REMOVE, SDHCI_INT_CARD_INT
> > > 
> > > Special care shall be put on SDHCI_INT_CARD_INT, which indicates
> > > interrupt generated by SD card.
> > > According to "SD Host Controller Simplified Spec. ver 3.00" when
> > > bit 8 (Card Interrupt Status Enable) at "Normal Interrupt Status
> > > Enable Register" (offset 0x34) is set, the card interrupt
> > > detection is started. Then eMMC card may cause the SD controller
> > > to set this bit and then this interrupt is passed to booted OS
> > > and might cause kernel crash.
> > > 
> > > 
> > > To sum up:
> > > - Only enable interrupts, which are served at u-boot
> > > - This cleanup as a side effect fixes SDHCI's CARD INTERRUPT
> > > problem at Linux kernel (versions 3.6+, sdhci controller)
> > > - Keep masked bits at "Normal Interrupt Signal Enable
> > > Register" (0x38h)
> > > 
> > > Signed-off-by: Lukasz Majewski <l.majewski at samsung.com>
> > > Signed-off-by: Kyungmin Park <kyungmin.park at samsung.com>
> > > Cc: Lei Wen <leiwen at marvell.com>
> > > Cc: Andy Fleming <afleming at freescale.com>
> > > ---
> > >  drivers/mmc/sdhci.c |    8 +++++---
> > >  1 files changed, 5 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/drivers/mmc/sdhci.c b/drivers/mmc/sdhci.c
> > > index 0fd1337..76c14fb 100644
> > > --- a/drivers/mmc/sdhci.c
> > > +++ b/drivers/mmc/sdhci.c
> > > @@ -412,9 +412,11 @@ int sdhci_init(struct mmc *mmc)
> > >  			status = sdhci_readl(host,
> > > SDHCI_PRESENT_STATE); }
> > >  
> > > -	/* Eable all state */
> > > -	sdhci_writel(host, SDHCI_INT_ALL_MASK, SDHCI_INT_ENABLE);
> > > -	sdhci_writel(host, SDHCI_INT_ALL_MASK,
> > > SDHCI_SIGNAL_ENABLE);
> > > +	/* Enable only interrupts served by the SD controller */
> > > +	sdhci_writel(host, SDHCI_INT_DATA_MASK |
> > > SDHCI_INT_CMD_MASK
> > > +		     , SDHCI_INT_ENABLE);
> > > +	/* Mask all sdhci interrupt sources */
> > > +	sdhci_writel(host, 0x0, SDHCI_SIGNAL_ENABLE);
> > >  
> > >  	return 0;
> > >  }
> > 
> > 
> > 
> 
> 
> 

-- 
Best regards,

Lukasz Majewski

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