Message ID | 1434469259-6474-1-git-send-email-linux_wi@tinag.ch |
---|---|
State | Accepted |
Headers | show |
On 06/16/2015 09:40 AM, Silvan Wicki wrote: > The Datasheet mentions on page 31 that the bits 10-31 must be read as > don't care and written as 0. > https://www.raspberrypi.org/wp-content/uploads/2012/02/BCM2835-ARM-Peripherals.pdf > > We cannot guarantee that we reed bits 10-31 as always 0 (becuase the > datasheet says read as don't care). We clear the bits with a bitmask to > prevent writing back unknown data at the reserved bits. I guess that's true. Acked-by: Stephen Warren <swarren@wwwdotorg.org> -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Jun 16, 2015 at 05:40:59PM +0200, Silvan Wicki wrote: > The Datasheet mentions on page 31 that the bits 10-31 must be read as > don't care and written as 0. > https://www.raspberrypi.org/wp-content/uploads/2012/02/BCM2835-ARM-Peripherals.pdf > > We cannot guarantee that we reed bits 10-31 as always 0 (becuase the > datasheet says read as don't care). We clear the bits with a bitmask to > prevent writing back unknown data at the reserved bits. > > Signed-off-by: Silvan Wicki <linux_wi@tinag.ch> Applied to for-next, thanks! If possible, use a spell checker on your commit message.
diff --git a/drivers/i2c/busses/i2c-bcm2835.c b/drivers/i2c/busses/i2c-bcm2835.c index c9336a3..aa06da1 100644 --- a/drivers/i2c/busses/i2c-bcm2835.c +++ b/drivers/i2c/busses/i2c-bcm2835.c @@ -50,6 +50,8 @@ #define BCM2835_I2C_S_CLKT BIT(9) #define BCM2835_I2C_S_LEN BIT(10) /* Fake bit for SW error reporting */ +#define BCM2835_I2C_BITMSK_S 0x03FF + #define BCM2835_I2C_TIMEOUT (msecs_to_jiffies(1000)) struct bcm2835_i2c_dev { @@ -111,6 +113,7 @@ static irqreturn_t bcm2835_i2c_isr(int this_irq, void *data) u32 val, err; val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S); + val &= BCM2835_I2C_BITMSK_S; bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_S, val); err = val & (BCM2835_I2C_S_CLKT | BCM2835_I2C_S_ERR);
The Datasheet mentions on page 31 that the bits 10-31 must be read as don't care and written as 0. https://www.raspberrypi.org/wp-content/uploads/2012/02/BCM2835-ARM-Peripherals.pdf We cannot guarantee that we reed bits 10-31 as always 0 (becuase the datasheet says read as don't care). We clear the bits with a bitmask to prevent writing back unknown data at the reserved bits. Signed-off-by: Silvan Wicki <linux_wi@tinag.ch> --- drivers/i2c/busses/i2c-bcm2835.c | 3 +++ 1 file changed, 3 insertions(+)