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    Subject[PATCH AUTOSEL 4.19 28/50] pinctrl: tegra: Fix write barrier placement in pmx_writel
    Date
    From: Sowjanya Komatineni <skomatineni@nvidia.com>

    [ Upstream commit c2cf351eba2ff6002ce8eb178452219d2521e38e ]

    pmx_writel uses writel which inserts write barrier before the
    register write.

    This patch has fix to replace writel with writel_relaxed followed
    by a readback and memory barrier to ensure write operation is
    completed for successful pinctrl change.

    Acked-by: Thierry Reding <treding@nvidia.com>
    Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
    Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
    Link: https://lore.kernel.org/r/1565984527-5272-2-git-send-email-skomatineni@nvidia.com
    Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/pinctrl/tegra/pinctrl-tegra.c | 4 +++-
    1 file changed, 3 insertions(+), 1 deletion(-)

    diff --git a/drivers/pinctrl/tegra/pinctrl-tegra.c b/drivers/pinctrl/tegra/pinctrl-tegra.c
    index 1aba75897d147..26a3f1eb9c6bf 100644
    --- a/drivers/pinctrl/tegra/pinctrl-tegra.c
    +++ b/drivers/pinctrl/tegra/pinctrl-tegra.c
    @@ -40,7 +40,9 @@ static inline u32 pmx_readl(struct tegra_pmx *pmx, u32 bank, u32 reg)

    static inline void pmx_writel(struct tegra_pmx *pmx, u32 val, u32 bank, u32 reg)
    {
    - writel(val, pmx->regs[bank] + reg);
    + writel_relaxed(val, pmx->regs[bank] + reg);
    + /* make sure pinmux register write completed */
    + pmx_readl(pmx, bank, reg);
    }

    static int tegra_pinctrl_get_groups_count(struct pinctrl_dev *pctldev)
    --
    2.20.1
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