linux-kernel - Re: [PATCH 1/3] [media] si2157: get chip id during probing

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Message-ID: <20170423143839.11187c09@aktux>
Date:   Sun, 23 Apr 2017 14:38:39 +0200
From:   Andreas Kemnade <andreas@...nade.info>
To:     Antti Palosaari <crope@....fi>
Cc:     mchehab@...nel.org, linux-media@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] [media] si2157: get chip id during probing

On Sun, 23 Apr 2017 15:19:21 +0300
Antti Palosaari <crope@....fi> wrote:

> On 03/16/2017 12:22 AM, Andreas Kemnade wrote:
> > If the si2157 is behind a e.g. si2168, the si2157 will
> > at least in some situations not be readable after the si268
> > got the command 0101. It still accepts commands but the answer
> > is just ffffff. So read the chip id before that so the
> > information is not lost.
> > 
> > The following line in kernel output is a symptome
> > of that problem:
> > si2157 7-0063: unknown chip version Si21255-\xffffffff\xffffffff\xffffffff
> That is hackish solution :( Somehow I2C reads should be get working 
> rather than making this kind of work-around. Returning 0xff to i2c reads 
> means that signal strength also shows some wrong static value?
> 
dvb-fe-tool -m is like this:

Lock   (0x1f) Signal= -1.00dBm C/N= 19.25dB UCB= 6061140 postBER= 40.0x10^-6

Signal strength is static.

Yes, I do not like my solution, too.
Also i2c reads from the windows driver from the si2157 after that 0101
command give such problems. I have checked my usb logs again.
So the question is where a better solution can come from.
I do not find a proper datasheet of the si2157 or the si2168.

Just for reference: the stick is labeled VG0022a.
The usb strings are like that:
  idVendor           0x1d19 Dexatek Technology Ltd.
  idProduct          0x0100 
  bcdDevice            1.00
  iManufacturer           1 ITE Tech., Inc.
  iProduct                2 TS Aggregator
  iSerial                 3 AF0102020700001

if that may lead to some information.

Regards,
Andreas

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