From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: MIME-Version: 1.0 References: <20181129130559.66732-1-chris.brandt@renesas.com> <20181129130559.66732-3-chris.brandt@renesas.com> <20181212021549.GA26333@bogus> In-Reply-To: From: Geert Uytterhoeven Date: Tue, 18 Dec 2018 08:42:36 +0100 Message-ID: Subject: Re: [PATCH 2/2] ARM: dts: r7s9210-rza2mevb: Add support for RZ/A2M EVB Content-Type: text/plain; charset="UTF-8" To: Chris Brandt Cc: Rob Herring , Kumar Gala , Simon Horman , Mark Rutland , "devicetree@vger.kernel.org" , "open list:MEDIA DRIVERS FOR RENESAS - FCP" List-ID: Hi Chris, On Mon, Dec 17, 2018 at 8:40 PM Chris Brandt wrote: > On Monday, December 17, 2018 1, linux-renesas-soc-owner@vger.kernel.org wrote: > > > Yup...there's the killer! > > > You'll notice that in mainline RZ/A devices, there is no QSPI driver, > > > and also the QSPI clock is left out of the list of HW clocks. Otherwise, > > > as you mentioned, that 'unused' clock would get shut off at the end of > > > boot...and you're whole system would stop immediately. > > > > If you had a simple driver with the binding as I proposed, then it > > could do the ioremap and clock management. And you could also have > > specific SPI and flash drivers for when you need to flashing without > > changing the DT. > > I agree. > > At the same time, this particular XIP-QSPI HW is now used in the latest > Renesas R-Car devices, and there has been some talk of upstreaming the > driver for it (as in, using it in SPI mode instead of XIP mode). > I'm waiting to see where that ends up, and if I should just use that > SPI mode driver for the RZ/A series but simply put in a new property like > "use-xip-mode;" that basically tells the driver to do nothing except enable > the clock (again) so it doesn't get shut off at the end of boot. The "clock management" should simply be calls to pm_runtime_enable() and pm_runtime_get_sync(). Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds