Hi Anurag,
Anurag Kumar Vulisha wrote:
> Gadget applications may have a requirement to disable the U1 and U2
> entry based on the usecase. For example, when performing performance
> benchmarking on mass storage gadget the U1 and U2 entries can be disabled.
> Another example is when periodic transfers like ISOC transfers are used
> with bInterval of 1 which doesn't require the link to enter into U1 or U2
> state (since ping is issued from host for every uframe interval). In this
> case the U1 and U2 entry can be disabled. This can be done by setting
> U1DevExitLat and U2DevExitLat values to 0 in the BOS descriptor. Host on
> seeing 0 value for U1DevExitLat and U2DevExitLat, it doesn't send SET_SEL
> commands to the gadget. Thus entry of U1 and U2 states can be avioded.
> This patch updates the same
I don't think we should assume that's the case for every host driver.
>
> Signed-off-by: Anurag Kumar Vulisha <anurag.kumar.vulisha@xxxxxxxxxx>
> ---
> drivers/usb/dwc3/core.c | 4 ++++
> drivers/usb/dwc3/core.h | 4 ++++
> drivers/usb/dwc3/gadget.c | 19 +++++++++++++++++++
> drivers/usb/dwc3/gadget.h | 6 ++++++
> 4 files changed, 33 insertions(+)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index a1b126f..4f0912c 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1285,6 +1285,10 @@ static void dwc3_get_properties(struct dwc3 *dwc)
> "snps,dis_u2_susphy_quirk");
> dwc->dis_enblslpm_quirk = device_property_read_bool(dev,
> "snps,dis_enblslpm_quirk");
> + dwc->dis_u1_entry_quirk = device_property_read_bool(dev,
> + "snps,dis_u1_entry_quirk");
> + dwc->dis_u2_entry_quirk = device_property_read_bool(dev,
> + "snps,dis_u2_entry_quirk");
Please use "-" rather than "_" in the property names.
> dwc->dis_rxdet_inp3_quirk = device_property_read_bool(dev,
> "snps,dis_rxdet_inp3_quirk");
> dwc->dis_u2_freeclk_exists_quirk = device_property_read_bool(dev,
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 1528d39..fa398e2 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -1015,6 +1015,8 @@ struct dwc3_scratchpad_array {
> * @dis_u2_susphy_quirk: set if we disable usb2 suspend phy
> * @dis_enblslpm_quirk: set if we clear enblslpm in GUSB2PHYCFG,
> * disabling the suspend signal to the PHY.
> + * @dis_u1_entry_quirk: set if link entering into U1 state needs to be disabled.
> + * @dis_u2_entry_quirk: set if link entering into U2 state needs to be disabled.
> * @dis_rxdet_inp3_quirk: set if we disable Rx.Detect in P3
> * @dis_u2_freeclk_exists_quirk : set if we clear u2_freeclk_exists
> * in GUSB2PHYCFG, specify that USB2 PHY doesn't
> @@ -1206,6 +1208,8 @@ struct dwc3 {
> unsigned dis_u3_susphy_quirk:1;
> unsigned dis_u2_susphy_quirk:1;
> unsigned dis_enblslpm_quirk:1;
> + unsigned dis_u1_entry_quirk:1;
> + unsigned dis_u2_entry_quirk:1;
> unsigned dis_rxdet_inp3_quirk:1;
> unsigned dis_u2_freeclk_exists_quirk:1;
> unsigned dis_del_phy_power_chg_quirk:1;
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index e293400..f2d3112 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -2073,6 +2073,24 @@ static int dwc3_gadget_stop(struct usb_gadget *g)
> return 0;
> }
>
> +static void dwc3_gadget_config_params(struct usb_gadget *g,
> + struct usb_dcd_config_params *params)
> +{
> + struct dwc3 *dwc = gadget_to_dwc(g);
> +
> + /* U1 Device exit Latency */
> + if (dwc->dis_u1_entry_quirk)
> + params->bU1devExitLat = 0;
> + else
> + params->bU1devExitLat = DWC3_DEFAULT_U1_DEV_EXIT_LAT;
> +
> + /* U2 Device exit Latency */
> + if (dwc->dis_u2_entry_quirk)
> + params->bU2DevExitLat = 0;
> + else
> + params->bU2DevExitLat = DWC3_DEFAULT_U2_DEV_EXIT_LAT;
> +}
> +
> static void dwc3_gadget_set_speed(struct usb_gadget *g,
> enum usb_device_speed speed)
> {
> @@ -2142,6 +2160,7 @@ static const struct usb_gadget_ops dwc3_gadget_ops = {
> .udc_start = dwc3_gadget_start,
> .udc_stop = dwc3_gadget_stop,
> .udc_set_speed = dwc3_gadget_set_speed,
> + .get_config_params = dwc3_gadget_config_params,
> };
>
> /* -------------------------------------------------------------------------- */
> diff --git a/drivers/usb/dwc3/gadget.h b/drivers/usb/dwc3/gadget.h
> index 3ed738e..5faf4d1 100644
> --- a/drivers/usb/dwc3/gadget.h
> +++ b/drivers/usb/dwc3/gadget.h
> @@ -48,6 +48,12 @@ struct dwc3;
> /* DEPXFERCFG parameter 0 */
> #define DWC3_DEPXFERCFG_NUM_XFER_RES(n) ((n) & 0xffff)
>
> +/* U1 Device exit Latency */
> +#define DWC3_DEFAULT_U1_DEV_EXIT_LAT 0x0A /* Less then 10 microsec */
> +
> +/* U2 Device exit Latency */
> +#define DWC3_DEFAULT_U2_DEV_EXIT_LAT 0x1FF /* Less then 511 microsec */
> +
> /* -------------------------------------------------------------------------- */
>
> #define to_dwc3_request(r) (container_of(r, struct dwc3_request, request))
Setting the exit latency for U1/U2 to 0 to prevent U1/U2 entry looks
more like a workaround than actually disabling U1/U2. There are
DCTL.INITU1/2ENA and DCTL.ACCEPTU1/2ENA for that.
Also, if these properties are set, then the device should rejects
SET_FEATURE(U1/U2) requests.
You can review Felipe's little code snippet from here to disable U1/U2:
https://marc.info/?l=linux-usb&m=155419284426942&w=2
BR,
Thinh
