From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marek Vasut Subject: Re: [PATCH V8 1/2] mtd: spi-nor: Bindings for Cadence Quad SPI Flash Controller driver. Date: Sat, 6 Feb 2016 08:42:38 +0100 Message-ID: <201602060842.38290.marex@denx.de> References: <1452486886-8049-1-git-send-email-marex@denx.de> <201602041225.11679.marex@denx.de> <56B38AB3.3070801@ti.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <56B38AB3.3070801-l0cyMroinI0@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: "R, Vignesh" Cc: Brian Norris , Rob Herring , "linux-mtd-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , Graham Moore , Alan Tull , David Woodhouse , Dinh Nguyen , Yves Vandervennet , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: devicetree@vger.kernel.org On Thursday, February 04, 2016 at 06:30:27 PM, R, Vignesh wrote: > On 2/4/2016 4:55 PM, Marek Vasut wrote: > > On Thursday, February 04, 2016 at 08:38:47 AM, Vignesh R wrote: > >> On 02/02/2016 02:43 AM, Marek Vasut wrote: > >>> On Monday, February 01, 2016 at 10:03:35 PM, Brian Norris wrote: > >>>> On Wed, Jan 13, 2016 at 03:39:17AM +0100, Marek Vasut wrote: > >>>>> On Wednesday, January 13, 2016 at 03:26:08 AM, Rob Herring wrote: > >>>>>> On Mon, Jan 11, 2016 at 05:34:45AM +0100, Marek Vasut wrote: > >> [...] > >> > >>>>> All these SoCs should be capable of tweaking the block to fit their > >>>>> needs by just the DT properties. I believe they differ only in the > >>>>> FIFO depth and sometimes someone is greedy and uses 4:16 CS > >>>>> multiplexer, which is an external passive component, but that's all. > >>>>> > >>>>> Would we need soc-specific compatible strings if this is the case? > >>>> > >>>> It's nice when most things can be supported with a small set of DT > >>>> properties, as you've done. But IUIC, I think it's usually good > >>>> practice to define and use SoC-specific (or maybe SoC family) > >>>> compatible strings in the docs and DTS files, in addition to the > >>>> generic one, in case there are future quirks that need to be handled. > >>>> Note that you don't actually have to use these in the driver yet, but > >>>> it's good to have a definition. > >>>> > >>>> So you can, today, have: > >>>> foo@xxxx { > >>>> > >>>> compatible = "ti,baz-12345", "cdns,qspi-nor"; > >>>> ... > >>>> > >>>> }; > >>>> > >>>> And we have the option to pick up "ti,baz-12345" in the Linux driver > >>>> *if needed.* > >> > >> The support for TI SoC that has this IP is not in upstream yet. I will > >> > >> add TI-specific compatible later. It will be: > >> foo@xxxx { > >> > >> compatible = "ti,k2g-qspi", "cdns,qspi-nor"; > >> > >> ... > >> > >> }; > > > > Do you expect any specifics which cannot be handled by the current > > bindings btw? > > > In my socfpga case, the compatible strings will be probably: > Yeah, there is delay(of few ns) required between writing to > INDIRECTWR_START bit and actually writing data to flash(i.e writesl() > call). This is specific to TI K2G SoC and needs to be tied to the new > binding. Can't you somehow poll the hardware to check whether or not it's ready instead of adding some random delay ? Best regards, Marek Vasut -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html