Re: [PATCH v2 1/3] usb: orion-echi: Add support for the Armada 3700

[Alan Stern]

On Thu, 9 Mar 2017, Gregory CLEMENT wrote:

> From: Hua Jing <jinghua@xxxxxxxxxxx>
> 
> - Add a new compatible string for the Armada 3700 SoCs
> 
> - add sbuscfg support for orion usb controller driver. For the SoCs
>   without hlock, need to program BAWR/BARD/AHBBRST fields in the sbuscfg
>   register to guarantee the AHB master's burst would not overrun or
>   underrun the FIFO.
> 
> - the sbuscfg register has to be set after the usb controller reset,
>   otherwise the value would be overridden to 0. In order to do this, the
>   reset callback is registered.
> 
> [gregory.clement@xxxxxxxxxxxxxxxxxx: - reword commit and comments
> 				     - fix checkpatch warning]
> Signed-off-by: Hua Jing <jinghua@xxxxxxxxxxx>
> Signed-off-by: Gregory CLEMENT <gregory.clement@xxxxxxxxxxxxxxxxxx>
> ---
>  .../devicetree/bindings/usb/ehci-orion.txt         |  4 ++-
>  drivers/usb/host/ehci-orion.c                      | 39 ++++++++++++++++++++++
>  2 files changed, 42 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/usb/ehci-orion.txt b/Documentation/devicetree/bindings/usb/ehci-orion.txt
> index 17c3bc858b86..2855bae79fda 100644
> --- a/Documentation/devicetree/bindings/usb/ehci-orion.txt
> +++ b/Documentation/devicetree/bindings/usb/ehci-orion.txt
> @@ -1,7 +1,9 @@
>  * EHCI controller, Orion Marvell variants
>  
>  Required properties:
> -- compatible: must be "marvell,orion-ehci"
> +- compatible: must be one of the following
> +	"marvell,orion-ehci"
> +	"marvell,armada-3700-ehci"
>  - reg: physical base address of the controller and length of memory mapped
>    region.
>  - interrupts: The EHCI interrupt
> diff --git a/drivers/usb/host/ehci-orion.c b/drivers/usb/host/ehci-orion.c
> index ee8d5faa0194..762bba41e06d 100644
> --- a/drivers/usb/host/ehci-orion.c
> +++ b/drivers/usb/host/ehci-orion.c
> @@ -47,6 +47,21 @@
>  #define USB_PHY_IVREF_CTRL	0x440
>  #define USB_PHY_TST_GRP_CTRL	0x450
>  
> +#define USB_SBUSCFG		0x90
> +#define	    USB_SBUSCFG_BAWR_SHIFT	    0x6
> +#define	    USB_SBUSCFG_BARD_SHIFT	    0x3
> +#define	    USB_SBUSCFG_AHBBRST_SHIFT	    0x0

Shift amounts are just regular numbers.  Giving them in hex is 
confusing because it leads people to think the bit pattern has some 
particular significance, which it doesn't.  Which would you rather see: 
(0x24 << 0x12) or (0x24 << 18)?

> +
> +/* BAWR = BARD = 3 : Align read/write bursts packets larger than 128 bytes */
> +#define USB_SBUSCFG_BAWR_ALIGN_128B	(0x3 << USB_SBUSCFG_BAWR_SHIFT)
> +#define USB_SBUSCFG_BARD_ALIGN_128B	(0x3 << USB_SBUSCFG_BARD_SHIFT)
> +/* AHBBRST = 3	   : Align AHB Burst to INCR16 (64 bytes) */
> +#define USB_SBUSCFG_AHBBRST_INCR16	(0x3 << USB_SBUSCFG_AHBBRST_SHIFT)

Besides, since these shift amounts are each used only once, it would be
simpler (and easier to read!) to do:

+#define USB_SBUSCFG_BAWR_ALIGN_128B  (0x3 << 6)
+#define USB_SBUSCFG_BARD_ALIGN_128B  (0x3 << 3)
+/* AHBBRST = 3          : Align AHB Burst to INCR16 (64 bytes) */
+#define USB_SBUSCFG_AHBBRST_INCR16   (0x3 << 0)


> +
> +#define USB_SBUSCFG_DEF_VAL (USB_SBUSCFG_BAWR_ALIGN_128B	\
> +			     | USB_SBUSCFG_BARD_ALIGN_128B	\
> +			     | USB_SBUSCFG_AHBBRST_INCR16)
> +
>  #define DRIVER_DESC "EHCI orion driver"
>  
>  #define hcd_to_orion_priv(h) ((struct orion_ehci_hcd *)hcd_to_ehci(h)->priv)
> @@ -151,8 +166,31 @@ ehci_orion_conf_mbus_windows(struct usb_hcd *hcd,
>  	}
>  }
>  
> +static int ehci_orion_drv_reset(struct usb_hcd *hcd)
> +{
> +	struct device *dev = hcd->self.controller;
> +	int retval;
> +
> +	retval = ehci_setup(hcd);
> +	if (retval)
> +		dev_err(dev, "ehci_setup failed %d\n", retval);

Was lack of this error message in the original driver a source of 
problems?  If not, I submit that there's no good reason to add it.

> +
> +	/*
> +	 * For SoC without hlock, need to program sbuscfg value to guarantee
> +	 * AHB master's burst would not overrun or underrun FIFO.
> +	 *
> +	 * sbuscfg reg has to be set after usb controller reset, otherwise
> +	 * the value would be override to 0.
> +	 */
> +	if (of_device_is_compatible(dev->of_node, "marvell,armada-3700-ehci"))
> +		wrl(USB_SBUSCFG, USB_SBUSCFG_DEF_VAL);

Do you want to do this even when retval != 0?

Alan Stern

> +
> +	return retval;
> +}
> +
>  static const struct ehci_driver_overrides orion_overrides __initconst = {
>  	.extra_priv_size =	sizeof(struct orion_ehci_hcd),
> +	.reset = ehci_orion_drv_reset,
>  };
>  
>  static int ehci_orion_drv_probe(struct platform_device *pdev)
> @@ -310,6 +348,7 @@ static int ehci_orion_drv_remove(struct platform_device *pdev)
>  
>  static const struct of_device_id ehci_orion_dt_ids[] = {
>  	{ .compatible = "marvell,orion-ehci", },
> +	{ .compatible = "marvell,armada-3700-ehci", },
>  	{},
>  };
>  MODULE_DEVICE_TABLE(of, ehci_orion_dt_ids);
>