pinctrl: tegra: Flush pinctrl writes during resume

This patch adds pinctrl register read to flush all the prior pinctrl
writes and then adds barrier for pinctrl register read to complete
during resume to make sure all pinctrl changes are effective.
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/1565984527-5272-3-git-send-email-skomatineni@nvidia.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/tegra/pinctrl-tegra.c

@@ -677,6 +677,10 @@ static int tegra_pinctrl_resume(struct device *dev)
 			writel_relaxed(*backup_regs++, regs++);
 	}
 
+	/* flush all the prior writes */
+	readl_relaxed(pmx->regs[0]);
+	/* wait for pinctrl register read to complete */
+	rmb();
 	return 0;
 }