From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Ungerer Subject: Re: [PATCH v2] spi: orion: support armada extended baud rates Date: Sun, 07 Sep 2014 22:14:16 +1000 Message-ID: <540C4C18.5030903@uclinux.org> References: <1409835268-29555-1-git-send-email-gerg@uclinux.org> <5409057A.6090900@uclinux.org> <5409B68A.7010604@uclinux.org> <20140906120600.GA11500@arch.cereza> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20140906120600.GA11500-nAQHv47ARr+vIlHkl8J1cg@public.gmane.org> Sender: linux-spi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Ezequiel Garcia Cc: Geert Uytterhoeven , linux-spi , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Jason Cooper , Thomas Petazzoni , Gregory Clement , Andrew Lunn , Sebastian Hesselbarth List-Id: devicetree@vger.kernel.org Hi Ezequiel, On 06/09/14 22:06, Ezequiel Garcia wrote: > Hi Greg, > > (Ccing mvebu guys, full discussion here: http://www.spinics.net/lists/devicetree/msg47806.html) > > On 05 Sep 11:11 PM, Greg Ungerer wrote: >> On 05/09/14 17:36, Geert Uytterhoeven wrote: >>> No, the other way around (from most-specific to least-specific): >>> >>> compatible = "marvell,armada-spi", "marvell,orion-spi" >>> >>> So the Armada version is used if available, and the Orion version >>> is used as a fallback. > Since you are doing another spin, please split this in two patches. > The driver and devicetree binding documentation should be in one patch, > and the devicetree .dtsi change in another patch. > > By following Geert's request about the compatible, you make sure both > patches can be merged through different maintainers, and that an old devicetree > blob can be used safely. Sure, yes, I would prefer that too. I didn't do it for this because checkpatch complained for the spi-orion.c change in its own: WARNING: DT compatible string "marvell,armada-spi" appears un-documented -- check ./Documentation/devicetree/bindings/ #170: FILE: drivers/spi/spi-orion.c:412: + { .compatible = "marvell,armada-spi", .data = &armada_spi_dev_data, }, But I am happy to ignore that :-) >>> Also what about armada370-xp, armada375, armada380 >>> and any other variants out there? >> I don't know. I don't have access to functional specs for anything >> other than the 370. I expect they are probably the same though. >> (Can anyone confirm?) >> > Confirmed. Judging from the specs, seems the same SPI IP is on all the > Armada SoCs; you can do the 'armada-spi' compatible addition on 375 and 38x. > > Did a few tests on the AXP-GP board (which has an SPI flash) using > 'orion-spi' and 'armada-spi' compatibles. > > Tested-by: Ezequiel Garcia > Reviewed-by: Ezequiel Garcia Thanks, appreciate that. > I haven't been able to spot any speed difference, though (perhaps my > test is too limited?), so I wonder if there's any improvement with this > patch? Try setting a speed like 2MHz for an SPI device. It will fail because that is below the minimum divisor it can calculate with the old orion style behavior. I have an armada 370 based board with an ethernet switch that is controlled by SPI. Its typical SPI bus speed is 2MHz, that is how I came up against this. Regards Greg -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html