Re: [PATCH 2/3] usb: host: xhci-plat: add support for the R-Car H2 and M2 xHCI controllers

Hi Geert-san,

(2014/05/19 20:58), Geert Uytterhoeven wrote:

Hi Shimoda-san,

On Mon, May 19, 2014 at 12:08 PM, Yoshihiro Shimoda
[off-list ref] wrote:

< snip >

quoted

+config USB_XHCI_RCAR
+       tristate "xHCI support for Renesas R-Car SoCs"
+       select USB_XHCI_PLATFORM
+       depends on ARCH_SHMOBILE || COMPILE_TEST
+       ---help---
+         Say 'Y' to enable the support for the xHCI host controller
+         found in Renesas R-Car ARM SoCs.

Does R-Car Gen1 also have xHCI, and is it compatible?
If not, you may want to call this driver USB_XHCI_RCAR2.

R-Car Gen1 doesn't have xHCI.
However, next generation of R-Car may have xHCI. (But, I don't know it is compatible.)
If we call this driver "USB_XHCI_RCAR2", should we also change filename to "xhci-rcar2.[ch]"?

< snip >

quoted

 static int xhci_plat_start(struct usb_hcd *hcd)
 {
+       struct device_node *of_node = hcd->self.controller->of_node;
+
+       if (of_device_is_compatible(of_node, "renesas,r8a7790-xhci") ||
+           of_device_is_compatible(of_node, "renesas,r8a7790-xhci"))

r8a7791, as Magnus already pointed out.

Yes, I will correct this.

quoted

+               xhci_rcar_start(hcd);

If CONFIG_USB_XHCI_RCAR is not defined, xhci_rcar_start() is a dummy
function, but the of_device_is_compatible() checks will still be compiled in.

Hence perhaps an #ifdef CONFIG_USB_XHCI_RCAR is warranted here,
possibly combined with inclusion of a C-source file, like is done in
drivers/usb/host/ohci-hcd.c? It's up to the USB maintainer to decide this,
though.

This implementation is similar with the following patch. And the patch already got
"Acked-by" from Mathias Nyman of USB XHCI DRIVER's maintainer.

	http://marc.info/?l=linux-usb&m0014933101775&w=2

< snip >

quoted

@@ -165,6 +172,15 @@ static int xhci_plat_probe(struct platform_device *pdev)
                        goto unmap_registers;
        }

+       if (of_device_is_compatible(pdev->dev.of_node,
+                                   "renesas,r8a7790-xhci") ||
+           of_device_is_compatible(pdev->dev.of_node,
+                                   "renesas,r8a7791-xhci")) {
+               ret = xhci_rcar_init_quirk(pdev);

Same here.

Same above.

< snip >

quoted

--- /dev/null
+++ b/drivers/usb/host/xhci-rcar.c

quoted

+/* USB3.0 Configuraion */

Configuration

I ran the "aspell -c" command, and I found other 2 typos. ("Initilization" and "Porariy")
So, I will correct these typos.

< snip >

quoted

+       for (index = 0; index < fw->size; index += 4) {
+               for (data = 0, j = 3; j >= 0; j--) {
+                       if ((j + index) >= fw->size)
+                               continue;
+                       data |= fw->data[index + j] << (8 * j);
+               }

This is your custom get_unaligned_le32(), to avoid reading beyond the end
of the buffer if its size is not a multiple of 4 bytes?

Yes, I would like to avoid it.

Is there some way to just use get_unaligned_le32()?

Yes, I will remove the custom get_unaligned_le32() and add the following code.
Do you think that this code is good?

	int i;
	u32 data;
	u8 buf[4];
< snip >
	for (i = 0; i < fw->size; i += 4) {
		memset(buf, 0, sizeof(buf));
		memcpy(buf, &fw->data[i], min(sizeof(buf), fw->size - i));
		data = get_unaligned_le32(buf);

Best regards,
Yoshihiro Shimoda

If you want to keep it, I would rewrite it as

              for (data = 0, j = 3; j >= 0; j--) {
                      if ((j + index) < fw->size)
                              data |= fw->data[index + j] << (8 * j);
              }

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torval

-- 
Yoshihiro Shimoda
EC No.