Re: [PATCH] usb host: Faraday FUSBH200 HCD driver.

From: Yuan-Hsin Chen
Date: Wed Mar 20 2013 - 09:24:21 EST


On Tue, Mar 19, 2013 at 11:48 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
> On Tue, 19 Mar 2013, Yuan-Hsin Chen wrote:
>> > What about the port_status registers? They're not between command and
>> > async_next. If they aren't consistent with EHCI, it makes things a lot
>> > more complicated.
>> fusbh200 has only one port_status register with different offset,
>> 0x30, and the position of some bits are different from EHCI.

How about adding kernel configuration to adjust offset for FUSBH200 in
ehci_def.h? So port_status would be in offset 0x20 from ehci_regs.

For example,

/* ASYNCLISTADDR: offset 0x18 */
u32 async_next; /* address of next async queue head */

u32 reserved1[2];

/* TXFILLTUNING: offset 0x24 */
u32 txfill_tuning; /* TX FIFO Tuning register */
#define TXFIFO_DEFAULT (8<<16) /* FIFO burst threshold 8 */

u32 reserved2[6];

/* CONFIGFLAG: offset 0x40 */
u32 configured_flag;
#define FLAG_CF (1<<0) /* true: we'll support "high speed" */

u32 reserved1;
/* PORTSC: offset 0x44 */
u32 port_status[0]; /* up to N_PORTS */

Furthermore, there are PORT_POWER, PORT_OWNER, PORT_LED_XXX,
port_status of FUSBH200. Also PORT_OC and PORT_OCC are in another
register. Is it ok to use quirk flag also?

> That's pretty nasty. Integrating that with the standard EHCI driver
> would be considerably more difficult.
> Why was the FUSBH200 designed in this strange way? Why doesn't it use
> the standard EHCI register layout? Were the engineers at Faraday
> deliberately trying to make life harder for driver writers?
>> Also, usbmode_ex, hostpc, and txfill_tuning other than configured_flag
>> are non-existent in fusbh200. They are used in both ehci-hcd.c and
>> ehci-hub.c for several times.
> They are used only if the hardware supports them, that is, only if the
> ehci->has_hostpc flag is set.
> Alan Stern

Thank you for your help.

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