Hi Martin, On Tue, Feb 21, 2017 at 1:06 PM, Martin Fuzzey <mfuzzey@xxxxxxxxxxx> wrote: > Hi, > > I ran into a problem of "choppy" audio when using a USB codec on a i.MX53 > (with the chipidea driver) > The problem occurs on 4.4.47 but not on an old 3.19 > It also does not occur on the latest 4.10. > > The codec is : > > Bus 001 Device 003: ID 08bb:29c0 Texas Instruments Japan PCM2900C Audio > CODEC > Device Descriptor: > bLength 18 > bDescriptorType 1 > bcdUSB 2.00 > bDeviceClass 0 (Defined at Interface level) > bDeviceSubClass 0 > bDeviceProtocol 0 > bMaxPacketSize0 8 > idVendor 0x08bb Texas Instruments Japan > idProduct 0x29c0 PCM2900C Audio CODEC > bcdDevice 1.00 > iManufacturer 1 BurrBrown from Texas Instruments > iProduct 2 USB AUDIO CODEC > iSerial 0 > > > Bisecting between 3.19 and 4.4 narrows it down to this commit: > > commit e765bfb73ff711b1d139a4438af9ecedabb07d34 > Author: Peter Chen <peter.chen@xxxxxxxxxxxxx> > Date: Thu Jun 18 11:43:34 2015 +0800 > > usb: chipidea: imx: enable CI_HDRC_SET_NON_ZERO_TTHA > > For i.mx platform, set ttctrl.ttha with non-zero value only affects > sitd, and ehci core makes sure the schedule is not full when accepts > new request, so it will not occur the transaction which will acorss > the SoF. > > > And indeed reverting that fixes the problem on 4.4 > > I see that this has already been reverted in 4.5 by: > > commit 1bc7da87c7410c6990c3251589e3854e64c55af2 > Author: Peter Chen <peter.chen@xxxxxxx> > Date: Fri Jan 29 16:47:24 2016 +0800 > > Revert "usb: chipidea: imx: enable CI_HDRC_SET_NON_ZERO_TTHA" > > This reverts commit e765bfb73ff7. > > In the most of cases, we only use one transaction per frame and the > frame rate may be high, If the platforms want to support multiple > transactions but less frame rate cases like [1] and [2], it can set > "non-zero-ttctrl-ttha" at dts. > > [1] http://www.spinics.net/lists/linux-usb/msg123125.html > [2] http://www.spinics.net/lists/linux-usb/msg118679.html > > Signed-off-by: Peter Chen <peter.chen@xxxxxxx> > > > Which explains why 4.10 is ok. > > But, maybe this should be backported to 4.4 (old)stable? Yes, please submit the revert patch to stable. -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
