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MUSB timeout broken

PATCH Superseded Orjan Friberg 2 participants 2 messages Jul 4, 2011

Subsystems (2)
USB MUSB multipoint high speed dual-role controller

v1 of 2 Superseded Latest is v2 →

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Orjan Friberg

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#0 lore raw

PATCH 1/1 MUSB timeout broken

The following construct (musb_hcd.c, usb_lowlevel_init)

    timeout = musb_cfg.timeout;
         while (timeout--)
                 if (readb(&musbr->devctl) & MUSB_DEVCTL_HM)
                         break;

will leave timeout == -1 when the timeout is reached, hence the timeout detecting code that follows will not trigger:

         /* if musb core is not in host mode, then return */
         if (!timeout)
                 return -1;

Without the patch below, doing a 'usb reset' without a device connected makes it impossible to discover connected devices later. I have not investigated why this happens since the timeout logic was broken (and correcting that fixed the issue at hand).

Changed to pre-decrement since I assume the timeout value is not *that* exact.

Thanks,
Orjan

drivers/usb/musb/musb_hcd.c +1 -1
index 974bb31..adcf7f7 100644
@@ -1114,7 +1114,7 @@ int usb_lowlevel_init(void)
          * should be a usb device connected.
          */
         timeout = musb_cfg.timeout;
-       while (timeout--)
+       while (--timeout)
                 if (readb(&musbr->devctl) & MUSB_DEVCTL_HM)
                         break;
Signature · 2 lines
Orjan Friberg
FlatFrog Laboratories AB
#1 lore raw

PATCH 1/1 MUSB timeout broken

Dear Orjan Friberg,

Quoted 15 lines · In message <[email protected]> you wrote:

The following construct (musb_hcd.c, usb_lowlevel_init)

    timeout = musb_cfg.timeout;
         while (timeout--)
                 if (readb(&musbr->devctl) & MUSB_DEVCTL_HM)
                         break;

will leave timeout == -1 when the timeout is reached, hence the timeout detecting code that follows will not trigger:

         /* if musb core is not in host mode, then return */
         if (!timeout)
                 return -1;
Quoted 7 lines

Without the patch below, doing a 'usb reset' without a device connected makes it impossible to discover connected devices later. I have not investigated why this happens since the timeout logic was broken (and correcting that fixed the issue at hand).

Changed to pre-decrement since I assume the timeout value is not *that* exact.

Thanks for spotting and reporting.

Quoted 8 lines

Thanks,
Orjan

drivers/usb/musb/musb_hcd.c +0 -0
index 974bb31..adcf7f7 100644

drivers/usb/musb/musb_hcd.c int usb_lowlevel_init(void) · line 1119

Quoted 7 lines
drivers/usb/musb/musb_hcd.c +1 -1
@@ -1114,7 +1114,7 @@ int usb_lowlevel_init(void)
          * should be a usb device connected.
          */
         timeout = musb_cfg.timeout;
-       while (timeout--)
+       while (--timeout)
                 if (readb(&musbr->devctl) & MUSB_DEVCTL_HM)
                         break;

Unfortunately, your patch is white space corrupted, and missing a proper Signed-off-by: line.

Please fix and repost. Thanks.

Best regards,

Wolfgang Denk

Signature · 5 lines
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