On 14.03.2013, at 05:19, Thomas Abraham wrote:
> On 14 March 2013 05:29, Alexander Graf <agraf@xxxxxxx> wrote:
>> On my Exynos 5 based Arndale system, I need to pull the reset line down
>> and then let it go up again to actually perform a reset. Without that
>> reset, I can't find any USB hubs on my bus, rendering the USB controller
>> useless.
>>
>> We also only need to reset the line after the phy node has been found.
>> This way we don't accidently reserve the vbus GPIO pin, but later on
>> defer the creation of our controller, because the phy device tree node
>> hasn't been probed yet.
>>
>> This patch implements the above logic, making EHCI and OHCI work on
>> Arndale systems for me.
>>
>> Signed-off-by: Alexander Graf <agraf@xxxxxxx>
>> CC: Vivek Gautam <gautam.vivek@xxxxxxxxxxx>
>> CC: Jingoo Han <jg1.han@xxxxxxxxxxx>
>> CC: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
>> CC: Kukjin Kim <kgene.kim@xxxxxxxxxxx>
>> CC: Felipe Balbi <balbi@xxxxxx>
>> CC: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
>> CC: Doug Anderson <dianders@xxxxxxxxxxxx>
>>
>> ---
>>
>> v1 -> v2:
>>
>> - remove gpio_free call
>> - move reset logic after phy node search
>>
>> diff --git a/drivers/usb/host/ehci-s5p.c b/drivers/usb/host/ehci-s5p.c
>> index 20ebf6a..b29b2b8 100644
>> --- a/drivers/usb/host/ehci-s5p.c
>> +++ b/drivers/usb/host/ehci-s5p.c
>> @@ -103,9 +103,14 @@ static void s5p_setup_vbus_gpio(struct platform_device *pdev)
>> if (!gpio_is_valid(gpio))
>> return;
>>
>> - err = gpio_request_one(gpio, GPIOF_OUT_INIT_HIGH, "ehci_vbus_gpio");
>> - if (err)
>> + /* reset pulls the line down, then up again */
>> + err = gpio_request_one(gpio, GPIOF_OUT_INIT_LOW, "ehci_vbus_gpio");
>> + if (err) {
>> dev_err(&pdev->dev, "can't request ehci vbus gpio %d", gpio);
>> + return;
>> + }
>> + mdelay(1);
>> + __gpio_set_value(gpio, 1);
>> }
>>
>> static u64 ehci_s5p_dma_mask = DMA_BIT_MASK(32);
>> @@ -131,8 +136,6 @@ static int s5p_ehci_probe(struct platform_device *pdev)
>> if (!pdev->dev.coherent_dma_mask)
>> pdev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
>>
>> - s5p_setup_vbus_gpio(pdev);
>> -
>> s5p_ehci = devm_kzalloc(&pdev->dev, sizeof(struct s5p_ehci_hcd),
>> GFP_KERNEL);
>> if (!s5p_ehci)
>> @@ -152,6 +155,8 @@ static int s5p_ehci_probe(struct platform_device *pdev)
>> s5p_ehci->otg = phy->otg;
>> }
>>
>> + s5p_setup_vbus_gpio(pdev);
>> +
>> s5p_ehci->dev = &pdev->dev;
>>
>> hcd = usb_create_hcd(&s5p_ehci_hc_driver, &pdev->dev,
>
> Hi Alexander,
>
> This change, though it works for Exynos5250 based Arndale board, does
> not actually seem correct. On Arndale board, the on-board 4-port usb
> hub is self powered and hence the vbus 'enable' gpio line from
> Exynos5250 SoC is instead used as a "reset" signal for the on-board
> usb hub (and not as the vbus enable signal).
>
> Whereas, the driver uses the gpio used in 's5p_setup_vbus_gpio'
> function as just a mechanism to enable vbus for downstream devices. So
> the driver should not be modified as above to handle the board
> specific behavior.
>
> Instead, what needs to be done is, remove the "samsung,vbus-gpio"
> property from the usb2.0 node in dts files (this property is optional)
> for Arndale board. Then, during the machine_init, perform the reset
> sequencing as required.
>
> Ideally, the reset sequencing for the on-board AX88760 usb hub should
> have been handled in the driver for this device. I have not checked if
> there is a driver for this in the kernel.
I can see your point, but as I mentioned earlier there seems to be some timing issue here. By simply doing the reset a few ms earlier (in the first probe, before the driver detects that it needs to defer probing), I already can't find the hub on the bus later.
So I'm assuming that the same thing would also happen if I put it even earlier in machine init.
The change in this patch actually does a reset even on non-Arndale boards. By taking away power and returning power to the line, the chip will most likely have reset :). So even on non-Arndale boards, this should get the USB phy into a clean state regardless of where the bootloader left it, right?
Alex
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