[PATCH AUTOSEL 5.2 070/171] usb: dwc3: Fix core validation in probe, move after clocks are enabled

From: Sasha Levin
Date: Thu Jul 18 2019 - 23:59:21 EST

From: Enric Balletbo i Serra <enric.balletbo@xxxxxxxxxxxxx>

[ Upstream commit dc1b5d9aed1794b5a1c6b0da46e372cc09974cbc ]

The required clocks needs to be enabled before the first register
access. After commit fe8abf332b8f ("usb: dwc3: support clocks and resets
for DWC3 core"), this happens when the dwc3_core_is_valid function is
called, but the mentioned commit adds that call in the wrong place,
before the clocks are enabled. So, move that call after the
clk_bulk_enable() to ensure the clocks are enabled and the reset

I detected this while, as experiment, I tried to move the clocks and resets
from the glue layer to the DWC3 core on a Samsung Chromebook Plus.

That was not detected before because, in most cases, the glue layer
initializes SoC-specific things and then populates the child "snps,dwc3"
with those clocks already enabled.

Fixes: b873e2d0ea1ef ("usb: dwc3: Do core validation early on probe")
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@xxxxxxxxxxxxx>
Signed-off-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
drivers/usb/dwc3/core.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 4aff1d8dbc4f..6e9e172010fc 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -1423,11 +1423,6 @@ static int dwc3_probe(struct platform_device *pdev)
dwc->regs = regs;
dwc->regs_size = resource_size(&dwc_res);

- if (!dwc3_core_is_valid(dwc)) {
- dev_err(dwc->dev, "this is not a DesignWare USB3 DRD Core\n");
- return -ENODEV;
- }

dwc->reset = devm_reset_control_get_optional_shared(dev, NULL);
@@ -1460,6 +1455,12 @@ static int dwc3_probe(struct platform_device *pdev)
if (ret)
goto unprepare_clks;

+ if (!dwc3_core_is_valid(dwc)) {
+ dev_err(dwc->dev, "this is not a DesignWare USB3 DRD Core\n");
+ ret = -ENODEV;
+ goto disable_clks;
+ }
platform_set_drvdata(pdev, dwc);

@@ -1525,6 +1526,7 @@ static int dwc3_probe(struct platform_device *pdev)

clk_bulk_disable(dwc->num_clks, dwc->clks);
clk_bulk_unprepare(dwc->num_clks, dwc->clks);