On Fri, Nov 06, 2015 at 04:34:19AM +0000, Yu, Xiangliang wrote: > > -----Original Message----- > > From: Mika Westerberg [mailto:mika.westerberg@xxxxxxxxxxxxxxx] > > Sent: Thursday, November 05, 2015 9:52 PM > > To: Yu, Xiangliang > > Cc: andriy.shevchenko@xxxxxxxxxxxxxxx; jarkko.nikula@xxxxxxxxxxxxxxx; > > wsa@xxxxxxxxxxxxx; linux-i2c@xxxxxxxxxxxxxxx; linux- > > kernel@xxxxxxxxxxxxxxx; Xue, Ken; Wan, Vincent; Huang, Ray; Wang, Annie; > > Li, Tony > > Subject: Re: [PATCH 1/1] I2C: designware: fix IO timeout issue for AMD > > controller > > > > On Thu, Nov 05, 2015 at 08:34:44PM +0800, Xiangliang Yu wrote: > > > Because of some hardware limitation, AMD I2C controller can't trigger > > > next interrupt if interrupt status has been changed after clearing > > > interrupt status bits. Then, I2C will lost interrupt and IO timeout. > > > > > > According to hardware design, this patch implements a workaround to > > > disable i2c controller interrupt after clearing interrupt bits when > > > entering ISR and to enable i2c interrupt before exiting ISR. > > > > > > To reduce the performance impacts on other vendors, use unlikely > > > function to check flag in ISR. > > > > > > Signed-off-by: Xiangliang Yu <Xiangliang.Yu@xxxxxxx> > > > --- > > > drivers/i2c/busses/i2c-designware-core.c | 6 ++++++ > > > drivers/i2c/busses/i2c-designware-core.h | 1 + > > > drivers/i2c/busses/i2c-designware-platdrv.c | 4 ++++ > > > 3 files changed, 11 insertions(+) > > > > > > diff --git a/drivers/i2c/busses/i2c-designware-core.c > > > b/drivers/i2c/busses/i2c-designware-core.c > > > index 7441cdc..04e7b65 100644 > > > --- a/drivers/i2c/busses/i2c-designware-core.c > > > +++ b/drivers/i2c/busses/i2c-designware-core.c > > > @@ -783,6 +783,9 @@ irqreturn_t i2c_dw_isr(int this_irq, void *dev_id) > > > > > > stat = i2c_dw_read_clear_intrbits(dev); > > > > What if the status changes right here, before you go and mask the interrupt? > Have no effect, because i2c controller can't trigger next interrupt. > > > > > > > > > + if (unlikely(dev->accessor_flags & ACCESS_INTR_MASK)) > > > + i2c_dw_disable_int(dev); > > > + > > > if (stat & DW_IC_INTR_TX_ABRT) { > > > dev->cmd_err |= DW_IC_ERR_TX_ABRT; > > > dev->status = STATUS_IDLE; > > > @@ -811,6 +814,9 @@ tx_aborted: > > > if ((stat & (DW_IC_INTR_TX_ABRT | DW_IC_INTR_STOP_DET)) || > > dev->msg_err) > > > complete(&dev->cmd_complete); > > > > > > + if (unlikely(dev->accessor_flags & ACCESS_INTR_MASK)) > > > + dw_writel(dev, DW_IC_INTR_DEFAULT_MASK, > > DW_IC_INTR_MASK); > > > > The driver disables TX interrupt when it is not needed anymore or when TX > > gets aborted but the above will re-enable all interrupts regardless. > > Is that the intention? > No, i2c controller can trigger next interrupt only after re-enable all interrupt. If you get an error the function masks all interrupts and jumps to tx_aborted label. With this patch you unmask all interrupts again before exiting the function. > > > > > + > > > return IRQ_HANDLED; > > > } > > > EXPORT_SYMBOL_GPL(i2c_dw_isr); > > > diff --git a/drivers/i2c/busses/i2c-designware-core.h > > > b/drivers/i2c/busses/i2c-designware-core.h > > > index 9630222..808ef6a 100644 > > > --- a/drivers/i2c/busses/i2c-designware-core.h > > > +++ b/drivers/i2c/busses/i2c-designware-core.h > > > @@ -111,6 +111,7 @@ struct dw_i2c_dev { > > > > > > #define ACCESS_SWAP 0x00000001 > > > #define ACCESS_16BIT 0x00000002 > > > +#define ACCESS_INTR_MASK 0x00000004 > > > > > > extern u32 dw_readl(struct dw_i2c_dev *dev, int offset); extern void > > > dw_writel(struct dw_i2c_dev *dev, u32 b, int offset); diff --git > > > a/drivers/i2c/busses/i2c-designware-platdrv.c > > > b/drivers/i2c/busses/i2c-designware-platdrv.c > > > index 472b882..0c59357 100644 > > > --- a/drivers/i2c/busses/i2c-designware-platdrv.c > > > +++ b/drivers/i2c/busses/i2c-designware-platdrv.c > > > @@ -251,6 +251,10 @@ static int dw_i2c_probe(struct platform_device > > *pdev) > > > dev->rx_fifo_depth = ((param1 >> 8) & 0xff) + 1; > > > dev->adapter.nr = pdev->id; > > > } > > > + > > > + if (!strncmp(pdev->name, "AMD0010", 7)) > > > + dev->accessor_flags |= ACCESS_INTR_MASK; > > > + > > > > Can't you put this to ->driver_data? For example it could refer to a > > configuration structure that then contains quirk flags. > I think it will need to add a function to support it, but the function > Is rarely used. It will easy to add if i2c driver has quirk mechanisms. > Added code is very simple and have no influence on others. What if the next AMD I2C controller needs another quirk, and then another? I would rather pass flags or similar (reference to config structure including flags) with ->driver_data. > > > > > > r = i2c_dw_init(dev); > > > if (r) > > > return r; > > > -- > > > 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
