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SubjectRE: [PATCH AUTOSEL 5.2 51/59] drm/exynos: fix missing decrement of retry counter
Date
From: Sasha Levin
> Sent: 06 August 2019 22:33
>
> From: Colin Ian King <colin.king@canonical.com>
>
> [ Upstream commit 1bbbab097a05276e312dd2462791d32b21ceb1ee ]
>
> Currently the retry counter is not being decremented, leading to a
> potential infinite spin if the scalar_reads don't change state.
>
> Addresses-Coverity: ("Infinite loop")
> Fixes: 280e54c9f614 ("drm/exynos: scaler: Reset hardware before starting the operation")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> Signed-off-by: Inki Dae <inki.dae@samsung.com>
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
> drivers/gpu/drm/exynos/exynos_drm_scaler.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_scaler.c b/drivers/gpu/drm/exynos/exynos_drm_scaler.c
> index ec9c1b7d31033..8989f8af716b7 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_scaler.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_scaler.c
> @@ -94,12 +94,12 @@ static inline int scaler_reset(struct scaler_context *scaler)
> scaler_write(SCALER_CFG_SOFT_RESET, SCALER_CFG);
> do {
> cpu_relax();
> - } while (retry > 1 &&
> + } while (--retry > 1 &&
> scaler_read(SCALER_CFG) & SCALER_CFG_SOFT_RESET);
> do {
> cpu_relax();
> scaler_write(1, SCALER_INT_EN);
> - } while (retry > 0 && scaler_read(SCALER_INT_EN) != 1);
> + } while (--retry > 0 && scaler_read(SCALER_INT_EN) != 1);
>
> return retry ? 0 : -EIO;

If the first loop hits the retry limit the second loop won't be right
and the final return value will be 0.

David

-
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