On Tue, Mar 24, 2020 at 11:28:11PM +0800, Kai-Heng Feng wrote:
> Nvidia card may come with a "phantom" UCSI device, and its driver gets
> stuck in probe routine, prevents any system PM operations like suspend.
>
> There's an unaccounted case that the target time can equal to jiffies in
> gpu_i2c_check_status(), let's solve that by using readl_poll_timeout()
> instead of jiffies comparison functions.
>
Thank you!
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> Fixes: c71bcdcb42a7 ("i2c: add i2c bus driver for NVIDIA GPU")
> Suggested-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx>
> ---
> v3:
> - Use readl_poll_timeout to make the retry loop simpler.
>
> v2:
> - Use a boolean to make sure the operation is timeout or not.
>
> drivers/i2c/busses/i2c-nvidia-gpu.c | 20 ++++++++------------
> 1 file changed, 8 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-nvidia-gpu.c b/drivers/i2c/busses/i2c-nvidia-gpu.c
> index 62e18b4db0ed..f5d25ce00f03 100644
> --- a/drivers/i2c/busses/i2c-nvidia-gpu.c
> +++ b/drivers/i2c/busses/i2c-nvidia-gpu.c
> @@ -8,6 +8,7 @@
> #include <linux/delay.h>
> #include <linux/i2c.h>
> #include <linux/interrupt.h>
> +#include <linux/iopoll.h>
> #include <linux/module.h>
> #include <linux/pci.h>
> #include <linux/platform_device.h>
> @@ -75,20 +76,15 @@ static void gpu_enable_i2c_bus(struct gpu_i2c_dev *i2cd)
>
> static int gpu_i2c_check_status(struct gpu_i2c_dev *i2cd)
> {
> - unsigned long target = jiffies + msecs_to_jiffies(1000);
> u32 val;
> + int ret;
>
> - do {
> - val = readl(i2cd->regs + I2C_MST_CNTL);
> - if (!(val & I2C_MST_CNTL_CYCLE_TRIGGER))
> - break;
> - if ((val & I2C_MST_CNTL_STATUS) !=
> - I2C_MST_CNTL_STATUS_BUS_BUSY)
> - break;
> - usleep_range(500, 600);
> - } while (time_is_after_jiffies(target));
> -
> - if (time_is_before_jiffies(target)) {
> + ret = readl_poll_timeout(i2cd->regs + I2C_MST_CNTL, val,
> + !(val & I2C_MST_CNTL_CYCLE_TRIGGER) ||
> + (val & I2C_MST_CNTL_STATUS) != I2C_MST_CNTL_STATUS_BUS_BUSY,
> + 500, 1000 * USEC_PER_MSEC);
> +
> + if (ret) {
> dev_err(i2cd->dev, "i2c timeout error %x\n", val);
> return -ETIMEDOUT;
> }
> --
> 2.17.1
>
--
With Best Regards,
Andy Shevchenko
