On Mon, Mar 21, 2016 at 12:32:27PM -0400, Jaret Cantu wrote:
> The TX settings can be calibrated for particular hardware. The
> phy is reset by Linux, so this cannot be handled by the bootloader.
>
> The TRM mentions that the maximum resistance should be used for the
> DN/DP calibration in order to pass USB certification.
>
> The values for the TX registers are poorly described in the TRM.
> The meanings of the register values were taken from another
> Freescale-provided document:
> https://community.freescale.com/message/566147#comment-566912
>
> Signed-off-by: Jaret Cantu <[email protected]>
> ---
> v3. Added unit suffix (-ohms) to tx-cal-45-d*
>
> v2. Copying devicetree list
> Removed prettifying extra whitespace
> Removed unnecessary register rewrite on resume
> Use min and max constants for clarity
>
> .../devicetree/bindings/phy/mxs-usb-phy.txt | 10 ++++
> drivers/usb/phy/phy-mxs-usb.c | 58
> ++++++++++++++++++++
> 2 files changed, 68 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/phy/mxs-usb-phy.txt
> b/Documentation/devicetree/bindings/phy/mxs-usb-phy.txt
> index 379b84a..1d25b04 100644
> --- a/Documentation/devicetree/bindings/phy/mxs-usb-phy.txt
> +++ b/Documentation/devicetree/bindings/phy/mxs-usb-phy.txt
> @@ -12,6 +12,16 @@ Required properties:
> - interrupts: Should contain phy interrupt
> - fsl,anatop: phandle for anatop register, it is only for imx6 SoC series
>
> +
> + if (!of_property_read_u32(np, "fsl,tx-d-cal", &val) &&
> + val >= MXS_PHY_TX_D_CAL_MIN && val <= MXS_PHY_TX_D_CAL_MAX) {
> + /* scale to 4-bit value */
> + val = (MXS_PHY_TX_D_CAL_MAX - val) * 0xF
> + / (MXS_PHY_TX_D_CAL_MAX - MXS_PHY_TX_D_CAL_MIN);
> + mxs_phy->tx_reg_mask |= GM_USBPHY_TX_D_CAL(~0);
> + mxs_phy->tx_reg_set |= GM_USBPHY_TX_D_CAL(val);
> + }
> +
I have tested "tx-d-cal", but it seems incorrect according to the xls you
have provided, would you please check it again or am I wrong?
dts changes:
+&usbphy1 {
+ fsl,tx-d-cal = <109>;
+};
+
+&usbphy2 {
+ fsl,tx-d-cal = <106>;
+};
+
The phy1's tx-d-cal is 0x3, and phy2's tx-d-cal is 0x4 after PHY
initialization,
but according to xls, it should be 0x4 and 0x5.
--
Best Regards,
Peter Chen
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