[U-Boot] [PATCH 02/15][v4] imx: usb: ehci-mx7 add usb driver for i.MX7D

[Marek Vasut]

On Friday, July 24, 2015 at 05:34:27 PM, Alonso Adrian wrote:
> Hi Marek,

Hi!

> > -----Original Message-----
> > From: Marek Vasut [mailto:marex at denx.de]
> > Sent: Friday, July 24, 2015 4:44 AM
> > To: Alonso Lazcano Adrian-B38018
> > Cc: u-boot at lists.denx.de; sbabic at denx.de; otavio at ossystems.com.br;
> > Estevam Fabio-R49496; Li Frank-B20596; Garg Nitin-B37173
> > Subject: Re: [PATCH 02/15][v4] imx: usb: ehci-mx7 add usb driver for
> > i.MX7D
> > 
> > On Thursday, July 23, 2015 at 09:25:17 PM, Adrian Alonso wrote:
> > > Add support for usb driver for i.MX7D SoC
> > > 
> > > Signed-off-by: Adrian Alonso <aalonso at freescale.com>
> > > Signed-off-by: Ye.Li <B37916 at freescale.com>
> > > Signed-off-by: Peng Fan <Peng.Fan at freescale.com>
> > 
> > So errr, why exactly can ehci-mx6 not be used here ? The code looks
> > almost like a copy of ehci-mx6 with minor tweaks here and there.
> > 
> > Best regards,
> > Marek Vasut
> 
> [Adrian] We can definitely have a single driver to support imx7 and imx6,
> but we mainly decide to have a driver for each SoC to try to make easier
> to maintain, there are so many variants of imx6
> (Quad/Dual/Solo/SoloX/QuadPlus/UL) and imx7 (Dual/Solo);

I just took a look into ehci-mx6.c and I see 1 (one) bogus conditional
which involves a board type. I see zero conditionals there which would
check CPU type.

> while there are
> several similarities in USB IP for iMX6 and iMX7, USB PHY Control and
> clock settings differ slightly making code harder to Understand and
> maintain in a single driver for imx7 and imx6.

The downside of having multiple copies of the code is that if you fix bug
in one copy and not in the other, the bug will remain unfixed on many of
the other machines. I don't like that. I am also not convinced that there
is justification for having separate drivers for MX6 and MX7 EHCI. I would
like to see a patch adding MX7 support into ehci-mx6 and in case it is
really as hairy as you say, I'd pick a separate one.

Best regards,
Marek Vasut