On Tue, Apr 03, 2018 at 11:48:45AM +0200, Maxime Ripard wrote: > On Tue, Mar 20, 2018 at 03:15:02PM +0800, Chen-Yu Tsai wrote: > > On Mon, Mar 19, 2018 at 5:31 AM, Maxime Ripard > > <maxime.ripard@xxxxxxxxxxx> wrote: > > > On Sat, Mar 17, 2018 at 05:28:47PM +0800, Chen-Yu Tsai wrote: > > >> From: Icenowy Zheng <icenowy@xxxxxxx> > > >> > > >> There's a GMAC configuration register, which exists on A64/A83T/H3/H5 in > > >> the syscon part, in the CCU of R40 SoC. > > >> > > >> Export a regmap of the CCU. > > >> > > >> Read access is not restricted to all registers, but only the GMAC > > >> register is allowed to be written. > > >> > > >> Signed-off-by: Icenowy Zheng <icenowy@xxxxxxx> > > >> Signed-off-by: Chen-Yu Tsai <wens@xxxxxxxx> > > > > > > Gah, this is crazy. I'm really starting to regret letting that syscon > > > in in the first place... > > > > IMHO syscon is really a better fit. It's part of the glue layer and > > most other dwmac user platforms treat it as such and use a syscon. > > Plus the controls encompass delays (phase), inverters (polarity), > > and even signal routing. It's not really just a group of clock controls, > > like what we poorly modeled for A20/A31. I think that was really a > > mistake. > > > > As I mentioned in the cover letter, a slightly saner approach would > > be to let drivers add custom syscon entries, which would then require > > less custom plumbing. > > A syscon is convenient, sure, but it also bypasses any abstraction > layer we have everywhere else, which means that we'll have to maintain > the register layout in each and every driver that uses it. > > So far, it's only be the GMAC, but it can also be others (the SRAM > controller comes to my mind), and then, if there's any difference in > the design in a future SoC, we'll have to maintain that in the GMAC > driver as well. I guess I forgot to say something, I'm fine with using a syscon we already have. I'm just questionning if merging any other driver using one is the right move. Maxime -- Maxime Ripard, Bootlin (formerly Free Electrons) Embedded Linux and Kernel engineering https://bootlin.com
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