jz-3.16 branch released - upstream status

Apelete Seketeli apelete at seketeli.net
Wed Sep 10 21:34:38 UTC 2014

Hi Maarten,

First of all, thank you very much for taking the time to give a clear
status; this might prove helpful to pick up some patches and resume
hacking on it.

On Tue, Sep-09-2014 at 03:47:01 PM +0200, Maarten ter Huurne wrote:
> On Tuesday 09 September 2014 00:53:46 Apelete Seketeli wrote:
> > Maarten ter Huurne (14):
> >   fbcon: Add 6x10 font
> I just submitted this upstream.
> >   /dev/mem: Add kernel config option to omit this device
> I submitted this a while ago and got the review comment that /dev/mem should 
> be made into a module. I agree, but I haven't done that work yet.

Very nice, thanks.

> >   mtd: cc_ftl: New FTL driver for media players using China Chip
> >     firmware
> This driver is pretty dirty; it cannot be submitted as-is. It was useful on 
> the Dingoo A320 to interoperate with the native OS partition, but it is not 
> useful on pure Linux devices like the GCW Zero and CI20. So both the 
> motivation and the urgency to clean it up are pretty low, which in practice 
> means it won't happen.
> >   media: radio: RDA5807: Added driver.
> This is not mature enough yet to submit. The GCW Zero uses the same radio 
> chip though, so we are still interested in developing it further. It is very 
> much an optional feature for the A320, since you only need it to listen to 
> FM radio.

I never noticed the radio patch before actually :).
Patches intended for Dingoo A320 will probably stay as they are since
I personally don't own one. Unless someone has one and care enough...

> >   MIPS: Removed declaration of obsolete arch_init_clk_ops()
> I just submitted this upstream.


> >   MIPS: JZ4740: Added setting of PLL rate and main dividers
> >   MIPS: JZ4740: Add cpufreq support
> >   MMC: JZ4740: Added support for CPU frequency changing
> There was also a patch to support runtime updates to some of the generic 
> cpufreq tables. I think it was dropped because it created complex merge 
> conflicts on recent kernels. Without that patch, the cpufreq support isn't 
> all that useful.
> The reason cpufreq support was important on the Dingoo is that in particular 
> emulators needed all the performance they could get and the JZ4740 could be 
> overclocked quite a bit. It may not be as relevant to other systems. In any 
> case, the kernel is perfectly usable without this, so I consider it 
> optional.

If overclocking is the only use for these patches, they might as well
stay as they are at least for now.

> >   MIPS: JZ4740: SLCD framebufer driver
> >   MIPS: JZ4740: Work around fbcon logo crash with SLCD
> The SLCD driver is the most important missing piece for A320 support.

These one seem interesting to me even for the Ben NanoNote. 

I was under the impression that the LCD screen was working better with
Qi-kernel than mainline: using Qi-kernel the screen completely turns
off after a few minutes, but with mainline it just turns all white
with backlight on.

I need to check if it is still working that way with jz-3.16 and
current mainline though.

> The easiest solution would be to upstream the SLCD driver as a separate 
> driver. However, there is quite a lot of code overlap with the LCD driver.
> There are some features in the SLCD driver that are not in the LCD driver as 
> far as I know, like support for vsynced double buffering. However, these 
> would have to be implemented separately for LCD mode, since the timing is 
> quite different. We have this functionality in LCD mode on the GCW Zero 
> though, so that could be used as an example.
> The panel support is ugly. Originally I thought there wasn't a cleaner 
> solution, but I recently I saw these two drivers:
>   drivers/video/backlight/lcd.c
>   drivers/video/backlight/platform_lcd.c
> ...which despite the directory name are not backlight drivers, but panel 
> control code.

Thanks for the details, will certainly be helpful to clean up the SLCD

> >   MIPS: A320: Add SoC sound support for Dingoo A320
> >   MIPS: A320: Add Dingoo A320 board support
> This code would need another review pass before sending it upstream, but I 
> don't recall it containing any terrible hacks.
> It only makes sense though to submit it if we have SLCD support upstreamed 
> as well, since A320 without SLCD is not very useful.

Okay, good to know.

> >   OpenDingux: Add initrd
> This won't (and shouldn't) be accepted upstream.
> >   Add defconfig for the Dingoo A320
> I'm not sure how useful this is: without the initrd, you can't boot 
> OpenDingux. You could try to boot for example Debian, but then you'd likely 
> need different config options enabled, so the defconfig wouldn't match 
> anyway.

Will stay as they are then, I guess.

Quick recount:

- 3 out of 14 patches have been sent upstream,
- 4 out of 14 might be interesting to fix,
- 7 out of 14 would probably stay as is.

Thanks again Maarten !


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