On Sat, Feb 8, 2014 at 2:41 AM, Antti Palosaari <crope@xxxxxx> wrote: > On 07.02.2014 22:54, Manu Abraham wrote: >> >> On Sat, Feb 8, 2014 at 1:19 AM, David Jedelsky <david.jedelsky@xxxxxxxxx> >> wrote: >>>> >>>> That changes I2C functionality from STOP + START to repeated START. >>>> Current functionality looks also very weird, as there is 5 messages >>>> sent, >>>> all with STOP condition. I am not surprised if actually bug is still in >>>> adapter... Somehow it should be first resolved how those messages are >>>> send, >>>> with repeated START or STOP. And fix I2C client or adapter or both. >>>> >>>> regards >>>> Antti >>> >>> >>> >>> >>> Manu, Antti, >>> >>> Thank you for your response. I agree that the code is somewhat peculiar >>> and >>> it could be worthy to review it using documentation before I leave it as >>> bug >>> in my hw. Unfortunately I don't own appropriate documentation. If you can >>> supply it I can look at it. >> >> >> I can assure you that the STB0899 driver works well for S2 with most >> USB bridges and PCI bridges, which brings me to the fact that the issue >> does not exist with the STB0899 driver. >> >> Regarding the documentation, I don't have any wrt to the USB bridge, but >> only for the demodulator, tuner. But my hands are tied on that front, due >> to >> NDA's and agreements. >> >> Looking further in my hardware museum, I did find a >> Technisat Skystar USB2 HD CI REV 2.0 >> >> The information on a white sticker on the PCB states: >> Model AD-SB301, Project ID: 6027 >> DVB-S2, CI, USB Box (on-line update) >> H/W Ver: A1, PID/VID: 14F7 / 0002 >> >> manufactured and sent to me by Azurewave. >> >> It has a broken ferrite cored inductor on it, which appears to be on the >> power line to the demodulator/tuner. >> >> The PID/VID looks exactly the same as yours. If you have a firmware bug, >> maybe it helps to update the firmware online ? (I guess the windows driver >> uses some stock Cypress driver, from what I can imagine ?) >> >> I had similar problems as you state, when I worked with a prototype >> version >> of the Mantis PCI chipset where it had some issues regarding repeated >> starts. I can't really remember the exact issue back then, but I do >> remember >> the issue being tuner related as well, since the write to the tuner would >> reach >> the very first tuner register alone. The communications to the tuner are >> through a repeater on the demodulator. >> >> This issue was addressed with an ECO Metal fix for the PCI bridge, but >> that >> did eventually result in a newer chip though. >> >> The problem could likely be similar with your USB bridge. Maybe it is a >> driver bug too .. I haven't looked deeply at the az6027 driver. > > > It is almost 100% sure I2C adapter or client bug. az6027 driver i2c adapter > seems to have some weird looking things, it behaves differently according > I2C slave address used. If I didn't read code wrong, in that case it does to > branch "if (msg[i].addr == 0xd0)". And looking that logic reveals it > supports only 2 I2C transfers: ACK. I looked at the code, just now. The I2C interface code looks garbage! > for reg read: START + write + REPEATED START + read + STOP > for reg write: START + write + STOP > > So that read operation (START + read + STOP) used by STB0899 is not > implemented at all. To be a bit more specific; the STB0899 S2 part. The STB0899 has a different (but standard) I2C interface for the DVB-S demodulator and a different one with 16/32 bit registers for the DVB-S2 demodulator. The USB-I2C interface code for the bridge doesn't implement this interface. But I see some still more weirdness in there with comments; "/* demod 16 bit addr */". There's a knot in my head, right now. AFAICS, the overall I2C communication with the STB0899 is very standard, generic I2C according to the official I2C specifications and documentations. All STB0899 specific handling is done within the demodulator read/write routines. If the I2C host interface with the USB device works in a standard way, then the device should work as-is with no changes to any frontend drivers. Regards, Manu -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
