[U-Boot] [PATCH RFC] usb: Prevent using reserved registers on DM36x usb

[Marek Vasut <marex@denx.de>]

Dear Andrew Murray,

> The musb driver defines and uses MUSB_CSR0_H_DIS_PING, however this
> bit is reserved on the DM36x. Thus this patch ensures that the
> reserved bit is not accesssed.
> 
> It has been observed that some USB devices will fail to enumerate
> with errors such as 'error in inquiry' without this patch.
> 
> See http://www.ti.com/litv/pdf/sprufh9a for details.
> 
> Cc: Marek Vasut <marex@denx.de>
> Cc: Tom Rini <trini@ti.com>
> Signed-off-by: Andrew Murray <amurray@embedded-bits.co.uk>
> ---
>  drivers/usb/musb/musb_core.h |    4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/usb/musb/musb_core.h b/drivers/usb/musb/musb_core.h
> index ec8a038..c9a9d66 100644
> --- a/drivers/usb/musb/musb_core.h
> +++ b/drivers/usb/musb/musb_core.h
> @@ -216,7 +216,11 @@ struct musb_regs {
>  #define MUSB_CSR0_P_SENTSTALL	0x0004
> 
>  /* CSR0 in Host mode */
> +#if defined(CONFIG_SOC_DM365)
> +#define MUSB_CSR0_H_DIS_PING		0x0000
> +#else
>  #define MUSB_CSR0_H_DIS_PING		0x0800
> +#endif
>  #define MUSB_CSR0_H_WR_DATATOGGLE	0x0400	/* Set to allow setting: */
>  #define MUSB_CSR0_H_DATATOGGLE		0x0200	/* Data toggle control 
*/
>  #define MUSB_CSR0_H_NAKTIMEOUT		0x0080

It would be much nicer if you avoided using this bit in musb_hcd.c instead of 
hacking it like this.

Best regards,
Marek Vasut