On 21:22 26-Apr 2015 Mikhail wrote:
> On 20:20 26-Apr 2015 Stefan Sperling wrote:
> > On Sun, Apr 26, 2015 at 01:31:17PM +0200, Stefan Sperling wrote:
> > > On Sun, Apr 19, 2015 at 11:48:32PM +0300, Mikhail wrote:
> > > > Bellow new version of the patch with above things fixed, also I've fixed
> > > > detection of ETV chip in urtwn_attach(), nothing else is changed.
> > >
> > > I'm seeing very low data transmission rates with your patch and a
> > > TP-Link TL-WN725N device. In both 11b and 11g mode, the data rate
> > > remains very low (less than 100Kbit/s). A different urtwn(4) device
> > > (with 8188CUS chip) has much better throughput.
> > >
> > > Are you seeing this, too?
> >
> > The chunk below is wrong for OpenBSD since it sets the intitial transmit
> > rate to an 11n rate. 0x13 corresponds to the "MCS7" 11n rate,
> > see linux/drivers/net/wireless/rtlwifi/rtl8188ee/def.h enum
> > rtl_desc92c_rate.
> > The value 11 corresponds to OFDM 54Mbit which is fine for OpenBSD.
> > We only support 11a/b/g at present.
> >
> > --- sys/dev/usb/if_urtwn.c 14 Mar 2015 03:38:49 -0000 1.43
> > +++ sys/dev/usb/if_urtwn.c 19 Apr 2015 20:27:41 -0000
> > @@ -1813,7 +2011,10 @@ urtwn_tx(struct urtwn_softc *sc, struct
> > txd->txdw4 |= htole32(SM(R92C_TXDW4_RTSRATE, 8));
> > txd->txdw5 |= htole32(0x0001ff00);
> > /* Send data at OFDM54. */
> > - txd->txdw5 |= htole32(SM(R92C_TXDW5_DATARATE, 11));
> > + if (sc->chip & URTWN_CHIP_88E)
> > + txd->txdw5 |= htole32(0x13 & 0x3f);
> > + else
> > + txd->txdw5 |= htole32(SM(R92C_TXDW5_DATARATE, 11));
> >
> > } else {
> > txd->txdw1 |= htole32(
> >
> > Reverting this change doesn't fix the transmit speed problem, unfortunately.
> >
> > I wonder if we're making some mistake while setting up the TX descriptor?
> > There are several differences in the TX descriptors of 88E vs 92C.
> > For example, 88E has third antenna C available.
>
> Hello, in urtwn_init(), in part:
>
> if (sc->chip & URTWN_CHIP_88E)
> urtwn_write_1(sc, R92C_RXDMA_AGG_PG_TH + 1, 4);
> else
> urtwn_write_1(sc, R92C_USB_DMA_AGG_TO, 4);
>
> comment first 3 lines. It fixes speed problem for me, but I need to
> understand the issue further, before proposing any solution.
The issue isn't in those lines, but a little bit higher - the driver
enables usb and dma aggregations, but native linux implementation
enables only dma and disables usb one.
I've submitted bug report to FreeBSD[1] with a patch, which I see as a
proper solution:
urtwn_write_1(sc, R92C_USB_SPECIAL_OPTION,
urtwn_read_1(sc, R92C_USB_SPECIAL_OPTION) |
- R92C_USB_SPECIAL_OPTION_AGG_EN);
+ (sc->chip & URTWN_CHIP_88E ?
+ ~R92C_USB_SPECIAL_OPTION_AGG_EN :
+ R92C_USB_SPECIAL_OPTION_AGG_EN));
I'd suggest to wait some time for feedback. Testing is welcome, of
course. Thank you for pointing this out and review in general.
[1] - https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=199718
