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Subject[PATCH] usb: dwc2: detect power supplies to reduce spam
Date
By statically hardcoding at compile time the number of supplies
("#define DWC2_NUM_SUPPLIES ARRAY_SIZE(dwc2_hsotg_supply_names)"), the
driver assumed that every controller uses supplies and issued a
warning if none were detected via the device tree [1], even though the
vast majority of devices (with 1 exception from Samsung) don't need
nor use them.

So to return to normality and stop warning everyone unconditionally,
detect if there are any supplies and no-op just like the dummy
regulator which got loudly auto-asigned does.

This issue has been previously discussed based on an alternative fix
at [2] a year back but nothing came out of it then.

[1]
dwc2 3f980000.usb: 3f980000.usb supply vusb_d not found, using dummy regulator
dwc2 3f980000.usb: 3f980000.usb supply vusb_a not found, using dummy regulator

[2]
https://www.spinics.net/lists/linux-usb/msg153010.html

Signed-off-by: Ioan-Adrian Ratiu <adi@adirat.com>
---
drivers/usb/dwc2/core.h | 5 +++--
drivers/usb/dwc2/platform.c | 46 +++++++++++++++++++++++++++++++--------------
2 files changed, 35 insertions(+), 16 deletions(-)

diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
index cd77af3b1565..c50b9fc4a162 100644
--- a/drivers/usb/dwc2/core.h
+++ b/drivers/usb/dwc2/core.h
@@ -128,7 +128,7 @@ static const char * const dwc2_hsotg_supply_names[] = {
"vusb_a", /* analog USB supply, 1.1V */
};

-#define DWC2_NUM_SUPPLIES ARRAY_SIZE(dwc2_hsotg_supply_names)
+#define DWC2_MAX_SUPPLIES ARRAY_SIZE(dwc2_hsotg_supply_names)

/*
* EP0_MPS_LIMIT
@@ -921,7 +921,8 @@ struct dwc2_hsotg {
struct phy *phy;
struct usb_phy *uphy;
struct dwc2_hsotg_plat *plat;
- struct regulator_bulk_data supplies[DWC2_NUM_SUPPLIES];
+ struct regulator_bulk_data supplies[DWC2_MAX_SUPPLIES];
+ u8 num_supplies;
u32 phyif;

spinlock_t lock;
diff --git a/drivers/usb/dwc2/platform.c b/drivers/usb/dwc2/platform.c
index 4703478f702f..3acf658af4e9 100644
--- a/drivers/usb/dwc2/platform.c
+++ b/drivers/usb/dwc2/platform.c
@@ -126,10 +126,12 @@ static int __dwc2_lowlevel_hw_enable(struct dwc2_hsotg *hsotg)
struct platform_device *pdev = to_platform_device(hsotg->dev);
int ret;

- ret = regulator_bulk_enable(ARRAY_SIZE(hsotg->supplies),
- hsotg->supplies);
- if (ret)
- return ret;
+ if (hsotg->num_supplies) {
+ ret = regulator_bulk_enable(hsotg->num_supplies,
+ hsotg->supplies);
+ if (ret)
+ return ret;
+ }

if (hsotg->clk) {
ret = clk_prepare_enable(hsotg->clk);
@@ -186,8 +188,9 @@ static int __dwc2_lowlevel_hw_disable(struct dwc2_hsotg *hsotg)
if (hsotg->clk)
clk_disable_unprepare(hsotg->clk);

- ret = regulator_bulk_disable(ARRAY_SIZE(hsotg->supplies),
- hsotg->supplies);
+ if (hsotg->num_supplies)
+ ret = regulator_bulk_disable(hsotg->num_supplies,
+ hsotg->supplies);

return ret;
}
@@ -210,6 +213,7 @@ int dwc2_lowlevel_hw_disable(struct dwc2_hsotg *hsotg)

static int dwc2_lowlevel_hw_init(struct dwc2_hsotg *hsotg)
{
+ struct regulator *reg;
int i, ret;

hsotg->reset = devm_reset_control_get_optional(hsotg->dev, "dwc2");
@@ -290,16 +294,30 @@ static int dwc2_lowlevel_hw_init(struct dwc2_hsotg *hsotg)
dev_dbg(hsotg->dev, "cannot get otg clock\n");
}

- /* Regulators */
- for (i = 0; i < ARRAY_SIZE(hsotg->supplies); i++)
- hsotg->supplies[i].supply = dwc2_hsotg_supply_names[i];
+ /* Regulators, vast majority of dwc2 devices don't use them at all */
+ for (i = 0; i < DWC2_MAX_SUPPLIES; i++) {
+ reg = regulator_get_optional(hsotg->dev,
+ dwc2_hsotg_supply_names[i]);
+
+ /* All or nothing (bulk): regs either are or aren't present */
+ if (IS_ERR(reg)) {
+ while (--i >= 0) {
+ regulator_put(hsotg->supplies[i].consumer);
+ hsotg->supplies[i].consumer = NULL;
+ hsotg->supplies[i].supply = NULL;
+ --hsotg->num_supplies;
+ }
+ break;
+ }

- ret = devm_regulator_bulk_get(hsotg->dev, ARRAY_SIZE(hsotg->supplies),
- hsotg->supplies);
- if (ret) {
- dev_err(hsotg->dev, "failed to request supplies: %d\n", ret);
- return ret;
+ hsotg->supplies[i].consumer = reg;
+ hsotg->supplies[i].supply = dwc2_hsotg_supply_names[i];
+ ++hsotg->num_supplies;
}
+
+ WARN_ON(hsotg->num_supplies &&
+ hsotg->num_supplies != DWC2_MAX_SUPPLIES);
+
return 0;
}

--
2.16.2
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