[1/2] usb: misc: onboard_usb_hub: Add support for clock input
Commit Message
From: Frieder Schrempf <frieder.schrempf@kontron.de>
Most onboard USB hubs have a dedicated crystal oscillator but on some
boards the clock signal for the hub is provided by the SoC.
In order to support this, we add the possibility of specifying a
clock in the devicetree that gets enabled/disabled when the hub
is powered up/down.
Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
---
drivers/usb/misc/onboard_usb_hub.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
Comments
On Thu, Nov 23, 2023 at 02:47:20PM +0100, Frieder Schrempf wrote:
> From: Frieder Schrempf <frieder.schrempf@kontron.de>
>
> Most onboard USB hubs have a dedicated crystal oscillator but on some
> boards the clock signal for the hub is provided by the SoC.
>
> In order to support this, we add the possibility of specifying a
> clock in the devicetree that gets enabled/disabled when the hub
> is powered up/down.
>
> Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
> ---
> drivers/usb/misc/onboard_usb_hub.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/drivers/usb/misc/onboard_usb_hub.c b/drivers/usb/misc/onboard_usb_hub.c
> index a341b2fbb7b44..e710e3c82ba9b 100644
> --- a/drivers/usb/misc/onboard_usb_hub.c
> +++ b/drivers/usb/misc/onboard_usb_hub.c
> @@ -5,6 +5,7 @@
> * Copyright (c) 2022, Google LLC
> */
>
> +#include <linux/clk.h>
> #include <linux/device.h>
> #include <linux/export.h>
> #include <linux/gpio/consumer.h>
> @@ -60,12 +61,19 @@ struct onboard_hub {
> bool going_away;
> struct list_head udev_list;
> struct mutex lock;
> + struct clk *clk;
> };
>
> static int onboard_hub_power_on(struct onboard_hub *hub)
> {
> int err;
>
> + err = clk_prepare_enable(hub->clk);
> + if (err) {
> + dev_err(hub->dev, "failed to enable clock: %d\n", err);
> + return err;
> + }
But what happens if clk is not set here?
And doesn't clk_prepare_enable() print out a message if it fails?
thanks,
greg k-h
Hello,
On Thu, Nov 23, 2023 at 01:55:57PM +0000, Greg Kroah-Hartman wrote:
> On Thu, Nov 23, 2023 at 02:47:20PM +0100, Frieder Schrempf wrote:
> > + err = clk_prepare_enable(hub->clk);
> > + if (err) {
> > + dev_err(hub->dev, "failed to enable clock: %d\n", err);
> > + return err;
I suggest to use %pe (and ERR_PTR(err)) here.
> > + }
>
> But what happens if clk is not set here?
clk_prepare_enable() just does "return 0" if the clk argument is NULL.
> And doesn't clk_prepare_enable() print out a message if it fails?
clk_prepare_enable is silent on errors.
Best regards
Uwe
Hi Greg, hi Uwe,
thanks for reviewing!
On 23.11.23 18:36, Uwe Kleine-König wrote:
> Hello,
>
> On Thu, Nov 23, 2023 at 01:55:57PM +0000, Greg Kroah-Hartman wrote:
>> On Thu, Nov 23, 2023 at 02:47:20PM +0100, Frieder Schrempf wrote:
>>> + err = clk_prepare_enable(hub->clk);
>>> + if (err) {
>>> + dev_err(hub->dev, "failed to enable clock: %d\n", err);
>>> + return err;
>
> I suggest to use %pe (and ERR_PTR(err)) here.
Ok, I added this in v2. I also added a patch to convert the other error
logs to be consistent within the driver.
>
>>> + }
>>
>> But what happens if clk is not set here?
>
> clk_prepare_enable() just does "return 0" if the clk argument is NULL.
Exactly!
>
>> And doesn't clk_prepare_enable() print out a message if it fails?
>
> clk_prepare_enable is silent on errors.
Right!
Thanks
Frieder
@@ -5,6 +5,7 @@
* Copyright (c) 2022, Google LLC
*/
+#include <linux/clk.h>
#include <linux/device.h>
#include <linux/export.h>
#include <linux/gpio/consumer.h>
@@ -60,12 +61,19 @@ struct onboard_hub {
bool going_away;
struct list_head udev_list;
struct mutex lock;
+ struct clk *clk;
};
static int onboard_hub_power_on(struct onboard_hub *hub)
{
int err;
+ err = clk_prepare_enable(hub->clk);
+ if (err) {
+ dev_err(hub->dev, "failed to enable clock: %d\n", err);
+ return err;
+ }
+
err = regulator_bulk_enable(hub->pdata->num_supplies, hub->supplies);
if (err) {
dev_err(hub->dev, "failed to enable supplies: %d\n", err);
@@ -92,6 +100,8 @@ static int onboard_hub_power_off(struct onboard_hub *hub)
return err;
}
+ clk_disable_unprepare(hub->clk);
+
hub->is_powered_on = false;
return 0;
@@ -266,6 +276,10 @@ static int onboard_hub_probe(struct platform_device *pdev)
return err;
}
+ hub->clk = devm_clk_get_optional(dev, NULL);
+ if (IS_ERR(hub->clk))
+ return dev_err_probe(dev, PTR_ERR(hub->clk), "failed to get clock\n");
+
hub->reset_gpio = devm_gpiod_get_optional(dev, "reset",
GPIOD_OUT_HIGH);
if (IS_ERR(hub->reset_gpio))