| Message ID | 1396534327-12971-1-git-send-email-richard.genoud@gmail.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On Thu, 3 Apr 2014 16:12:07 +0200, Richard Genoud wrote: > rt2x00usb_register_read_lock() calls rt2x00usb_vendor_req_buff_lock() > that calls rt2x00usb_vendor_request() which is already looping up to > REGISTER_BUSY_COUNT times. > > So this loop is not needed. Not true. rt2x00usb_vendor_request() busy-waits for usb_control_msg() to succeed, rt2x00usb_register_read_lock() busy-waits for the register field itself to become 0. Also, how would this be a BUG? -- kuba -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
2014-04-03 17:37 GMT+02:00 Jakub Kici?ski <moorray3@wp.pl>: > On Thu, 3 Apr 2014 16:12:07 +0200, Richard Genoud wrote: >> rt2x00usb_register_read_lock() calls rt2x00usb_vendor_req_buff_lock() >> that calls rt2x00usb_vendor_request() which is already looping up to >> REGISTER_BUSY_COUNT times. >> >> So this loop is not needed. > > Not true. rt2x00usb_vendor_request() busy-waits for usb_control_msg() > to succeed, rt2x00usb_register_read_lock() busy-waits for the register > field itself to become 0. > > Also, how would this be a BUG? Ok, you're right. Just forget about this patch... Richard -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Apr 03, 2014 at 05:37:01PM +0200, Jakub Kici?ski wrote: > On Thu, 3 Apr 2014 16:12:07 +0200, Richard Genoud wrote: > > rt2x00usb_register_read_lock() calls rt2x00usb_vendor_req_buff_lock() > > that calls rt2x00usb_vendor_request() which is already looping up to > > REGISTER_BUSY_COUNT times. > > > > So this loop is not needed. > > Not true. rt2x00usb_vendor_request() busy-waits for usb_control_msg() > to succeed, rt2x00usb_register_read_lock() busy-waits for the register > field itself to become 0. Yeah, but still we are looping REGISTER_BUSY_COUNT*REGISTER_BUSY_COUNT what seems to be far too long. Stanislaw -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, 4 Apr 2014 10:19:09 +0200, Stanislaw Gruszka wrote: > On Thu, Apr 03, 2014 at 05:37:01PM +0200, Jakub Kici?ski wrote: > > On Thu, 3 Apr 2014 16:12:07 +0200, Richard Genoud wrote: > > > rt2x00usb_register_read_lock() calls rt2x00usb_vendor_req_buff_lock() > > > that calls rt2x00usb_vendor_request() which is already looping up to > > > REGISTER_BUSY_COUNT times. > > > > > > So this loop is not needed. > > > > Not true. rt2x00usb_vendor_request() busy-waits for usb_control_msg() > > to succeed, rt2x00usb_register_read_lock() busy-waits for the register > > field itself to become 0. > > Yeah, but still we are looping REGISTER_BUSY_COUNT*REGISTER_BUSY_COUNT > what seems to be far too long. Yes, the busy waiting itself takes roughly 1s (100*100*100us) and then there are transfer times, so it might be too long indeed. Vendor driver waits only 10 * 5ms in RTUSB_VendorRequest() so rt2x00usb_vendor_request() seems like a better place to cut down the number of loops. Alternatively we could make rt2x00usb_regbusy_read() check the retval from rt2x00usb_vendor_request() and exit early? -- kuba -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, Apr 04, 2014 at 11:01:06AM +0200, Jakub Kici?ski wrote: > On Fri, 4 Apr 2014 10:19:09 +0200, Stanislaw Gruszka wrote: > > On Thu, Apr 03, 2014 at 05:37:01PM +0200, Jakub Kici?ski wrote: > > > On Thu, 3 Apr 2014 16:12:07 +0200, Richard Genoud wrote: > > > > rt2x00usb_register_read_lock() calls rt2x00usb_vendor_req_buff_lock() > > > > that calls rt2x00usb_vendor_request() which is already looping up to > > > > REGISTER_BUSY_COUNT times. > > > > > > > > So this loop is not needed. > > > > > > Not true. rt2x00usb_vendor_request() busy-waits for usb_control_msg() > > > to succeed, rt2x00usb_register_read_lock() busy-waits for the register > > > field itself to become 0. > > > > Yeah, but still we are looping REGISTER_BUSY_COUNT*REGISTER_BUSY_COUNT > > what seems to be far too long. > > Yes, the busy waiting itself takes roughly 1s (100*100*100us) and then > there are transfer times, so it might be too long indeed. Vendor driver > waits only 10 * 5ms in RTUSB_VendorRequest() so We use "timeout" argument which is set to 500ms , so perhaps that could be the reason why Richard sees "infinite" loop i.e. 100*100*(500ms + 100us) > rt2x00usb_vendor_request() seems like a better place to cut down the > number of loops. > > Alternatively we could make rt2x00usb_regbusy_read() check the retval > from rt2x00usb_vendor_request() and exit early? Make sense, but I think we should review the area and make some more changes to fine tune the timeout of USB reg reading functions. Stanislaw -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
2014-04-04 16:06 GMT+02:00 Stanislaw Gruszka <sgruszka@redhat.com>: > On Fri, Apr 04, 2014 at 11:01:06AM +0200, Jakub Kici?ski wrote: >> On Fri, 4 Apr 2014 10:19:09 +0200, Stanislaw Gruszka wrote: >> > On Thu, Apr 03, 2014 at 05:37:01PM +0200, Jakub Kici?ski wrote: >> > > On Thu, 3 Apr 2014 16:12:07 +0200, Richard Genoud wrote: >> > > > rt2x00usb_register_read_lock() calls rt2x00usb_vendor_req_buff_lock() >> > > > that calls rt2x00usb_vendor_request() which is already looping up to >> > > > REGISTER_BUSY_COUNT times. >> > > > >> > > > So this loop is not needed. >> > > >> > > Not true. rt2x00usb_vendor_request() busy-waits for usb_control_msg() >> > > to succeed, rt2x00usb_register_read_lock() busy-waits for the register >> > > field itself to become 0. >> > >> > Yeah, but still we are looping REGISTER_BUSY_COUNT*REGISTER_BUSY_COUNT >> > what seems to be far too long. >> >> Yes, the busy waiting itself takes roughly 1s (100*100*100us) and then >> there are transfer times, so it might be too long indeed. Vendor driver >> waits only 10 * 5ms in RTUSB_VendorRequest() so > > We use "timeout" argument which is set to 500ms , so perhaps that > could be the reason why Richard sees "infinite" loop i.e. > 100*100*(500ms + 100us) That's what I thougth at the begining, so I applied this patch, but it was still looping on errors -EPROTO. >> rt2x00usb_vendor_request() seems like a better place to cut down the >> number of loops. >> >> Alternatively we could make rt2x00usb_regbusy_read() check the retval >> from rt2x00usb_vendor_request() and exit early? > > Make sense, but I think we should review the area and make some more > changes to fine tune the timeout of USB reg reading functions. > > Stanislaw -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/net/wireless/rt2x00/rt2x00usb.c b/drivers/net/wireless/rt2x00/rt2x00usb.c index 10572452cc21..14142b099019 100644 --- a/drivers/net/wireless/rt2x00/rt2x00usb.c +++ b/drivers/net/wireless/rt2x00/rt2x00usb.c @@ -148,12 +148,9 @@ int rt2x00usb_regbusy_read(struct rt2x00_dev *rt2x00dev, if (!test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags)) return -ENODEV; - for (i = 0; i < REGISTER_BUSY_COUNT; i++) { - rt2x00usb_register_read_lock(rt2x00dev, offset, reg); - if (!rt2x00_get_field32(*reg, field)) - return 1; - udelay(REGISTER_BUSY_DELAY); - } + rt2x00usb_register_read_lock(rt2x00dev, offset, reg); + if (!rt2x00_get_field32(*reg, field)) + return 1; rt2x00_err(rt2x00dev, "Indirect register access failed: offset=0x%.08x, value=0x%.08x\n", offset, *reg);
rt2x00usb_register_read_lock() calls rt2x00usb_vendor_req_buff_lock() that calls rt2x00usb_vendor_request() which is already looping up to REGISTER_BUSY_COUNT times. So this loop is not needed. Signed-off-by: Richard Genoud <richard.genoud@gmail.com> --- drivers/net/wireless/rt2x00/rt2x00usb.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-)