Hi Alexander,
(copying my comments from v3 to keep the discussion on the latest version)
On Wed, Jul 27, 2022 at 04:11:16PM +0200, Alexander Stein wrote:
> Despite default reset upon probe, release reset line after powering up
> the hub and assert reset again before powering down.
>
> Signed-off-by: Alexander Stein <alexander.stein@xxxxxxxxxxxxxxx>
> ---
> * Patch 1 dropped as it already applied
>
> Changes in v4:
> * Rebased to [1] commit e0c6b1f3d757 ("USB: usbsevseg: convert sysfs snprintf to sysfs_emit")
> * Added platform data for usb424
> Reset pulse length taken from [2], Table 3-2 Symbol RESET_N
> Completely untested
>
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git Branch usb-testing
> [2] http://ww1.microchip.com/downloads/en/devicedoc/00001692c.pdf
>
> drivers/usb/misc/onboard_usb_hub.c | 28 ++++++++++++++++++++++++++++
> drivers/usb/misc/onboard_usb_hub.h | 22 +++++++++++++++++-----
> 2 files changed, 45 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/usb/misc/onboard_usb_hub.c b/drivers/usb/misc/onboard_usb_hub.c
> index de3627af3c84..0c81417dd9a7 100644
> --- a/drivers/usb/misc/onboard_usb_hub.c
> +++ b/drivers/usb/misc/onboard_usb_hub.c
> @@ -7,6 +7,7 @@
>
> #include <linux/device.h>
> #include <linux/export.h>
> +#include <linux/gpio/consumer.h>
> #include <linux/init.h>
> #include <linux/kernel.h>
> #include <linux/list.h>
> @@ -38,6 +39,8 @@ struct usbdev_node {
> struct onboard_hub {
> struct regulator *vdd;
> struct device *dev;
> + const struct onboard_hub_pdata *pdata;
> + struct gpio_desc *reset_gpio;
> bool always_powered_in_suspend;
> bool is_powered_on;
> bool going_away;
> @@ -56,6 +59,9 @@ static int onboard_hub_power_on(struct onboard_hub *hub)
> return err;
> }
>
> + fsleep(hub->pdata->reset_us);
> + gpiod_set_value_cansleep(hub->reset_gpio, 0);
> +
> hub->is_powered_on = true;
>
> return 0;
> @@ -65,6 +71,11 @@ static int onboard_hub_power_off(struct onboard_hub *hub)
> {
> int err;
>
> + if (hub->reset_gpio) {
> + gpiod_set_value_cansleep(hub->reset_gpio, 1);
> + fsleep(hub->pdata->reset_us);
Is this delay here actually needed? There is a delay in onboard_hub_power_on(),
before de-asserting the reset, isn't that enough?
> + }
> +
> err = regulator_disable(hub->vdd);
> if (err) {
> dev_err(hub->dev, "failed to disable regulator: %d\n", err);
> @@ -219,6 +230,7 @@ static void onboard_hub_attach_usb_driver(struct work_struct *work)
>
> static int onboard_hub_probe(struct platform_device *pdev)
> {
> + const struct of_device_id *of_id;
> struct device *dev = &pdev->dev;
> struct onboard_hub *hub;
> int err;
> @@ -227,10 +239,26 @@ static int onboard_hub_probe(struct platform_device *pdev)
> if (!hub)
> return -ENOMEM;
>
> + of_id = of_match_device(onboard_hub_match, &pdev->dev);
> + if (!of_id)
> + return -ENODEV;
> +
> + hub->pdata = of_id->data;
> + if (!hub->pdata)
> + return -EINVAL;
> +
> hub->vdd = devm_regulator_get(dev, "vdd");
> if (IS_ERR(hub->vdd))
> return PTR_ERR(hub->vdd);
>
> + hub->reset_gpio = devm_gpiod_get_optional(dev, "reset",
> + GPIOD_OUT_HIGH);
> + if (IS_ERR(hub->reset_gpio))
> + return dev_err_probe(dev, PTR_ERR(hub->reset_gpio), "failed to get reset GPIO\n");
> +
> + if (hub->reset_gpio)
> + fsleep(hub->pdata->reset_us);
Same question here: onboard_hub_power_on() is called a few lines below and
has a delay before de-asserting the reset. Is the delay here really needed?
