usb: phy: tegra: Add clarifying comments about the shared registers

Tools like Coccinelle may erroneously recommend to use the
devm_platform_ioremap_resource() API for the registers mapping because
these tools are not aware about the implementation details of the driver.
Let's add a clarifying comments to the code, which should help to stop
future attempts to break the driver.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Link: https://lore.kernel.org/r/20200202224259.29187-1-digetx@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/phy/phy-tegra-usb.c b/drivers/usb/phy/phy-tegra-usb.c
index 037e8ee..6153cc3 100644 (file)
--- a/drivers/usb/phy/phy-tegra-usb.c
+++ b/drivers/usb/phy/phy-tegra-usb.c
@@ -969,6 +969,10 @@ static int utmi_phy_probe(struct tegra_usb_phy *tegra_phy,
                return  -ENXIO;
        }
 
+       /*
+        * Note that UTMI pad registers are shared by all PHYs, therefore
+        * devm_platform_ioremap_resource() can't be used here.
+        */
        tegra_phy->pad_regs = devm_ioremap(&pdev->dev, res->start,
                                           resource_size(res));
        if (!tegra_phy->pad_regs) {
@@ -1087,6 +1091,10 @@ static int tegra_usb_phy_probe(struct platform_device *pdev)
                return  -ENXIO;
        }
 
+       /*
+        * Note that PHY and USB controller are using shared registers,
+        * therefore devm_platform_ioremap_resource() can't be used here.
+        */
        tegra_phy->regs = devm_ioremap(&pdev->dev, res->start,
                                       resource_size(res));
        if (!tegra_phy->regs) {