On 10/31/2014 02:31 PM, Dinh Nguyen wrote:
> On 10/31/2014 12:42 PM, Felipe Balbi wrote:
>> Hi,
>>
>> On Fri, Oct 31, 2014 at 10:20:06AM -0500, Dinh Nguyen wrote:
>>>>> @@ -339,7 +339,8 @@ static void dwc2_handle_wakeup_detected_intr(struct dwc2_hsotg *hsotg)
>>>>> }
>>>>> /* Change to L0 state */
>>>>> hsotg->lx_state = DWC2_L0;
>>>>> - call_gadget(hsotg, resume);
>>>>> + if (!IS_ERR(hsotg->clk))
>>>>> + call_gadget(hsotg, resume);
>>>>
>>>> instead of exposing the clock detail to the entire driver, add IS_ERR()
>>>> checks to resume and suspend instead. In fact, NULL is a valid clock, so
>>>> you might as well:
>>>>
>>>> clk = clk_get(foo, bar);
>>>> if (IS_ERR(clk))
>>>> dwc->clk = NULL;
>>>> else
>>>> dwc->clk = clk;
>>>>
>>>> Then you don't need any IS_ERR() checks sprinkled around the driver.
>>>
>>> But we would still need to check for the clock before accessing gadget
>>> functionality right?
>>>
>>> if (dwc2->clk)
>>> call_gadget();
>>
>> Read my comment again. "NULL is a valid clock". Look at what
>> clk_enable() does when a NULL pointer is passed:
>>
>> static int __clk_enable(struct clk *clk)
>> {
>> int ret = 0;
>>
>> if (!clk)
>> return 0;
>>
>> if (WARN_ON(clk->prepare_count == 0))
>> return -ESHUTDOWN;
>>
>> if (clk->enable_count == 0) {
>> ret = __clk_enable(clk->parent);
>>
>> if (ret)
>> return ret;
>>
>> if (clk->ops->enable) {
>> ret = clk->ops->enable(clk->hw);
>> if (ret) {
>> __clk_disable(clk->parent);
>> return ret;
>> }
>> }
>> }
>>
>> clk->enable_count++;
>> return 0;
>> }
>>
>> int clk_enable(struct clk *clk)
>> {
>> unsigned long flags;
>> int ret;
>>
>> flags = clk_enable_lock();
>> ret = __clk_enable(clk);
>> clk_enable_unlock(flags);
>>
>> return ret;
>> }
>> EXPORT_SYMBOL_GPL(clk_enable);
>
> Ah yes, thanks for the explanation. So if clk=NULL, it just return 0.
> But what I'm saying is that if the driver is configured for dual-role
> mode, and no clock is specified, then the driver should not be accessing
> any gadget functionality.
>
> So as the patch series stands right now, if I swap out an A connector to
> a B-connector, then I get a connect_id_status change interrupt. The
> status would show a device and I would initialize the gadget portion of
> the driver.
>
> diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
> index 44c609f..96810f7 100644
> --- a/drivers/usb/dwc2/hcd.c
> +++ b/drivers/usb/dwc2/hcd.c
> @@ -1371,7 +1371,8 @@ static void dwc2_conn_id_status_change(struct
> work_struct *work)
> hsotg->op_state = OTG_STATE_B_PERIPHERAL;
> dwc2_core_init(hsotg, false, -1);
> dwc2_enable_global_interrupts(hsotg);
> - s3c_hsotg_core_init(hsotg);
> + if (hsotg->clk)
> + s3c_hsotg_core_init(hsotg);
>
> So if I don't have a valid clock, I'll be accessing the peripheral
> portion of the IP.
>
> But I guess not having the check for the valid clock here should be fine
> as I don't see a case where there can be 2 different clocks for host and
> peripheral?
>
Ah...nevermind. I don't need to check for clocks at all because in
dwc2_gadget_init(), the clock node check comes before
usb_add_gadget_udc(). Thus without a clock node, gadget functionality is
disabled already.
Thanks,
Dinh
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