From mboxrd@z Thu Jan 1 00:00:00 1970 From: Grygorii Strashko Subject: Re: [PATCH 2/2] spi: davinci: support adding delay between transmission Date: Mon, 8 Sep 2014 16:30:57 +0300 Message-ID: <540DAF91.6090002@ti.com> References: <1408634706-5762-1-git-send-email-grygorii.strashko@ti.com> <1408634706-5762-3-git-send-email-grygorii.strashko@ti.com> <20140821182035.GM24407@sirena.org.uk> <53F74695.3010902@ti.com> <20140822150644.GX24407@sirena.org.uk> <5409C704.5070303@ti.com> <20140906143113.GI2601@sirena.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20140906143113.GI2601-GFdadSzt00ze9xe1eoZjHA@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: Errors-To: davinci-linux-open-source-bounces-VycZQUHpC/PFrsHnngEfi1aTQe2KTcn/@public.gmane.org To: Mark Brown Cc: devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, davinci-linux-open-source-VycZQUHpC/PFrsHnngEfi1aTQe2KTcn/@public.gmane.org, ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org, robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, santosh.shilimkar-l0cyMroinI0@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: devicetree@vger.kernel.org Hi Mark, On 09/06/2014 05:31 PM, Mark Brown wrote: > On Fri, Sep 05, 2014 at 05:21:56PM +0300, Grygorii Strashko wrote: > >> I think we have some misunderstanding here :( >> 1) All new properties a optional and should be specified for SPI Slave devices >> 2) Seems we are talking using different terms: >> - you referring to the term "transfers" - sequence of packets. >> Each packet is one transfer (array of words). >> - while these new properties affect on "transmissions" - sequence of words. >> Each word is one transmission. > > That's *very* unusual terminology which doesn't match my expectations at > all. Please describe words as words, that'll be much more obvious. These terms are used in DM/TRM :( I'll split this patch and first introduce WDELAY, C2TDELAY, T2CDELAY (with updated documentation). The only question is - Should they be somehow common or specific for spi-davinci? > >> Also, below is additional information about properties which >> are used in 5-pin mode (SPI_READY) to improve error detection >> [OMAP-L138/da830 - http://www.ti.com/lit/ug/spruh77a/spruh77a.pdf]: > > This is a *whole* other thing, please split these out and work on this > separately. The client device is going to need to be doing the same > thing here so implementing this as a local option in the controller > driver isn't the best way forwards. > >>>> SPIFMTn[23].PARPOL - Parity polarity: even or odd. PARPOL can be modified in privilege mode only. >>>> 0 An even parity flag is added at the end of the transmit data stream. >>>> 1 An odd parity flag is added at the end of the transmit data stream. > >>> Why would these be specified in DT and not with runtime flags enabled by >>> the device? It looks like they affect the data stream generated by the >>> controller so the client device needs to know about them; I'd expect >>> that it's device driver would be controlling when they are enabled if >>> the controller supports them. > >> Could you clarify, pls - Do you mean that struct spi_device.mode and >> common SPI DT bindings should be extended to support this? > > Yes, if they aren't something that's purely internal to the device they > need to be generic so that both devices can be configured appropriately. > Regards, -grygorii