Re: [linuxtv-commits] [hg:v4l-dvb] cx25840: fix determining the firmware name

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On Mon, 2009-09-07 at 03:06 -0300, Mauro Carvalho Chehab wrote:
> Em Mon, 7 Sep 2009 01:20:33 -0400
> Michael Krufky <mkrufky@xxxxxxxxxxxxxx> escreveu:
> 
> > On Mon, Sep 7, 2009 at 1:10 AM, Mauro Carvalho
> > Chehab<mchehab@xxxxxxxxxxxxx> wrote:
> > > Em Fri, 4 Sep 2009 14:05:31 -0400
> > > Michael Krufky <mkrufky@xxxxxxxxxxxxxx> escreveu:
> > >
> > >> Mauro,
> > >>
> > >> This fix should really go to Linus before 2.6.31 is released, if
> > >> possible.  It also should be backported to stable, but I need it in
> > >> Linus' tree before it will be accepted into -stable.
> > >>
> > >> Do you think you can slip this in before the weekend?  As I
> > >> understand, Linus plans to release 2.6.31 on Saturday, September 5th.
> > >>
> > >> If you dont have time for it, please let me know and I will send it in myself.
> > >>
> > >
> > > This patch doesn't apply upstream:
> > >
> > > $ patch -p1 -i 12613.patch
> > > patching file drivers/media/video/cx25840/cx25840-firmware.c
> > > Hunk #5 FAILED at 107.
> > > 1 out of 5 hunks FAILED -- saving rejects to file drivers/media/video/cx25840/cx25840-firmware.c.re
> > 
> > 
> > OK, this is going to need a manual backport.  This does fix an issue
> > in 2.6.31, and actually affects all kernels since the appearance of
> > the cx23885 driver, but I can wait until you push it to Linus in the
> > 2.6.32 merge window, then I'll backport & test it for -stable.
> 
> Ok. I think I asked you once, but let me re-ask again: from what I was told, the
> latest cx25840 firmware (the one that Conexant give us the distribution rights)
> seems to be common to several cx25840-based chips.

Well, I know they are all very similar.  I also know that the firmware
for the CX23418's integrated A/V Core *is different* from the
CX2584[0123]'s firmware.  The differences are subtle, but it is
different.  For example, compare
cx25840/cx25840-core.c:log_audio_status() with
cx18/cx18-av-core.c:log_audio_status().

I know the CX23418 A/V Core firmware isn't at issue with this change,
but the situation between the CX2584[0123], CX2388[578], and CX2310[12]
firmwares is likely similar.

Even if the firmwares are identical now, there is nothting inhbiting
Conexant from releasing firmware fixes for the CX2310[12] that are not
applicable to, and just wrong for, the CX25843 for example.


>  It would be really good if
> we can test it with all devices, especially since distros will add it on their
> firmware packages, as they are at the firmware -git

Working through the set of test vectors, that includes all the Worldwide
audio standards, while looking for subtle differences or malfunctions,
is likely more work than any perceived savings of using a single
firmware image.  How can anyone even tell if anything is misdetected
without professional TV standards signal generation equipment?  What if
using the wrong firmware introduces only an intermittent audio standard
misdetection on that core?

I'll assert we'll never be able to declare a reasonable testing success
for using an audio standard autodetection firmware not specifically
designated by Conexant to be for a particular Conexant A/V digitizer
core.  The core always ends up with subtle differences when integrated
into another chip.

I suppose one exception is if a "cmp" of two officially designated
firmware images show the images as being identical, then obviously that
images can be shared between those cores.


I assume licensing is really the issue here.  It is unfortunate.
However, in my opinion, it is better for the user to know that his
device is "broken" until he fetches the right firmware, than to spend
hours debugging mystery audio problems because the user thinks he is
using the "right" firmware when he is not.

Oh well, I'll stop rambling now...

Regards,
Andy

> Cheers,
> Mauro


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