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SubjectRe: [PATCH v5 2/5] usb: phy: Workaround for USB erratum-A005728
On Wed, 8 May 2019, Yinbo Zhu wrote:

> From: Suresh Gupta <B42813@freescale.com>
>
> PHY_CLK_VALID bit for UTMI PHY in USBDR does not set even
> if PHY is providing valid clock. Workaround for this
> involves resetting of PHY and check PHY_CLK_VALID bit
> multiple times. If PHY_CLK_VALID bit is still not set even
> after 5 retries, it would be safe to deaclare that PHY
> clock is not available.
> This erratum is applicable for USBDR less then ver 2.4.
>
> Signed-off-by: Suresh Gupta <B42813@freescale.com>
> Signed-off-by: Yinbo Zhu <yinbo.zhu@nxp.com>
> ---
> Change in v5:
> remove dev_err function unnecessary parameters
>
> drivers/usb/host/ehci-fsl.c | 37 ++++++++++++++++++++++++++-----------
> drivers/usb/host/ehci-fsl.h | 3 +++
> 2 files changed, 29 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/usb/host/ehci-fsl.c b/drivers/usb/host/ehci-fsl.c
> index 38674b7..1634ac8 100644
> --- a/drivers/usb/host/ehci-fsl.c
> +++ b/drivers/usb/host/ehci-fsl.c
> @@ -183,6 +183,17 @@ static int fsl_ehci_drv_probe(struct platform_device *pdev)
> return retval;
> }
>
> +static bool usb_phy_clk_valid(struct usb_hcd *hcd)
> +{
> + void __iomem *non_ehci = hcd->regs;
> + bool ret = true;
> +
> + if (!(ioread32be(non_ehci + FSL_SOC_USB_CTRL) & PHY_CLK_VALID))
> + ret = false;
> +
> + return ret;
> +}
> +
> static int ehci_fsl_setup_phy(struct usb_hcd *hcd,
> enum fsl_usb2_phy_modes phy_mode,
> unsigned int port_offset)
> @@ -226,6 +237,16 @@ static int ehci_fsl_setup_phy(struct usb_hcd *hcd,
> /* fall through */
> case FSL_USB2_PHY_UTMI:
> case FSL_USB2_PHY_UTMI_DUAL:
> + /* PHY_CLK_VALID bit is de-featured from all controller
> + * versions below 2.4 and is to be checked only for
> + * internal UTMI phy
> + */
> + if (pdata->controller_ver > FSL_USB_VER_2_4 &&
> + pdata->have_sysif_regs && !usb_phy_clk_valid(hcd)) {
> + dev_err(dev, "USB PHY clock invalid\n");
> + return -EINVAL;
> + }
> +
> if (pdata->have_sysif_regs && pdata->controller_ver) {
> /* controller version 1.6 or above */
> tmp = ioread32be(non_ehci + FSL_SOC_USB_CTRL);
> @@ -249,17 +270,11 @@ static int ehci_fsl_setup_phy(struct usb_hcd *hcd,
> break;
> }
>
> - /*
> - * check PHY_CLK_VALID to determine phy clock presence before writing
> - * to portsc
> - */
> - if (pdata->check_phy_clk_valid) {
> - if (!(ioread32be(non_ehci + FSL_SOC_USB_CTRL) &
> - PHY_CLK_VALID)) {
> - dev_warn(hcd->self.controller,
> - "USB PHY clock invalid\n");
> - return -EINVAL;
> - }
> + if (pdata->have_sysif_regs &&
> + pdata->controller_ver > FSL_USB_VER_1_6 &&
> + !usb_phy_clk_valid(hcd)) {

This is still wrong. The line above should be indented four characters
less than it is: the '!' should line up with the 'p' in the line above
it.

Alan Stern

> + dev_warn(hcd->self.controller, "USB PHY clock invalid\n");
> + return -EINVAL;
> }
>
> ehci_writel(ehci, portsc, &ehci->regs->port_status[port_offset]);
> diff --git a/drivers/usb/host/ehci-fsl.h b/drivers/usb/host/ehci-fsl.h
> index cbc4220..9d18c6e 100644
> --- a/drivers/usb/host/ehci-fsl.h
> +++ b/drivers/usb/host/ehci-fsl.h
> @@ -50,4 +50,7 @@
> #define UTMI_PHY_EN (1<<9)
> #define ULPI_PHY_CLK_SEL (1<<10)
> #define PHY_CLK_VALID (1<<17)
> +
> +/* Retry count for checking UTMI PHY CLK validity */
> +#define UTMI_PHY_CLK_VALID_CHK_RETRY 5
> #endif /* _EHCI_FSL_H */
>

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