On Fri, 5 Feb 2021 20:12:01 +0100 Pali Rohár <p...@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 <lu...@denx.de>
> Signed-off-by: Pali Rohár <p...@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: lu...@denx.de
pgpjHE5zNHUTN.pgp
Description: OpenPGP digital signature
