[RESEND PATCH 05/16] usb: musb: Fix configuring FIFO for endpoints

[Lukasz Majewski]

On Fri,  5 Feb 2021 20:12:01 +0100
Pali Rohár <pali at kernel.org> wrote:

> This patch fixes configuring FIFO for one-directional endpoints which
> have either RX or TX queue and therefore only one FIFO.
> 
> Size of FIFO buffer is 2^(idx+3) bytes and starting address is
> 2^(addr+3). Moreover first 64 bytes are reserved for EP0.
> 
> Without this patch if FIFO size specified by caller was zero then idx
> was incorrectly calculated (expr. ffs(0)-1) and size overflowed in
> fifosz register. This register uses has only 4 bits for FIFO size.
> Moreover specifying zero size is not possible.
> 
> This patch is fixing calculation of start address and buffer size to
> minimal value and ensure that it would not overlap with reserved EP0
> buffer.
> 
> This issue caused loose of packets on USB bus in both directions and
> basically usbtty was unusable.
> 

Reviewed-by: Lukasz Majewski <lukma at denx.de>

> Signed-off-by: Pali Rohár <pali at kernel.org>
> 
> ---
> Changes in v2:
> * Correctly calculate minimal buffer size
> * Store into fifoaddr address in musb units (8 bytes)
> ---
>  drivers/usb/musb/musb_core.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/musb/musb_core.c
> b/drivers/usb/musb/musb_core.c index cc6dc3839d..9651f074a4 100644
> --- a/drivers/usb/musb/musb_core.c
> +++ b/drivers/usb/musb/musb_core.c
> @@ -50,7 +50,7 @@ void musb_start(void)
>  # define config_fifo(dir, idx, addr) \
>  	do { \
>  		writeb(idx, &musbr->dir##fifosz); \
> -		writew(fifoaddr >> 3, &musbr->dir##fifoadd); \
> +		writew(addr, &musbr->dir##fifoadd); \
>  	} while (0)
>  #endif
>  
> @@ -66,14 +66,14 @@ void musb_start(void)
>  void musb_configure_ep(const struct musb_epinfo *epinfo, u8 cnt)
>  {
>  	u16 csr;
> -	u16 fifoaddr = 64; /* First 64 bytes of FIFO reserved for
> EP0 */
> +	u16 fifoaddr = 64 >> 3; /* First 64 bytes of FIFO reserved
> for EP0 */ u32 fifosize;
>  	u8  idx;
>  
>  	while (cnt--) {
>  		/* prepare fifosize to write to register */
>  		fifosize = epinfo->epsize >> 3;
> -		idx = ffs(fifosize) - 1;
> +		idx = fifosize ? ((ffs(fifosize) - 1) & 0xF) : 0;
>  
>  		writeb(epinfo->epnum, &musbr->index);
>  		if (epinfo->epdir) {
> @@ -99,7 +99,7 @@ void musb_configure_ep(const struct musb_epinfo
> *epinfo, u8 cnt) writew(csr | MUSB_RXCSR_FLUSHFIFO,
>  					&musbr->rxcsr);
>  		}
> -		fifoaddr += epinfo->epsize;
> +		fifoaddr += 1 << idx;
>  		epinfo++;
>  	}
>  }




Best regards,

Lukasz Majewski

--

DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma at denx.de
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