From mboxrd@z Thu Jan 1 00:00:00 1970 From: Subject: RE: support DUAL and QUAD[patch v1] Date: Tue, 16 Jul 2013 10:12:46 +0000 Message-ID: <593AEF6C47F46446852B067021A273D6D93B49E1@MUCSE039.lantiq.com> References: <20980858CB6D3A4BAE95CA194937D5E73E9E84D2@DBDE04.ent.ti.com> <20980858CB6D3A4BAE95CA194937D5E73E9E851E@DBDE04.ent.ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Cc: spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, sourav.poddar-l0cyMroinI0@public.gmane.org, broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, linux-mtd-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org To: , Return-path: In-Reply-To: <20980858CB6D3A4BAE95CA194937D5E73E9E851E-yXqyApvAXouIQmiDNMet8wC/G2K4zDHf@public.gmane.org> Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: spi-devel-general-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: linux-spi.vger.kernel.org Hello Pekon, Gupta, Pekon wrote on=A02013-07-16: > > > > Hi, Gupta > > > > > > > [Pekon]: Instead of adding new fields you can use existing 'mode' fie= ld to > > > pass on the platform specific configurations. And if 'u8 mode' does n= ot > > > suffice you can increase it to 'u32'. > > > #define QSPI_MODE 1 << 5; // just check which bit-fields are un= -used > > > spi_board_info->mode |=3D QSPI_MODE; > > > > > > > well, can dual and quad be regarded as a spi mode? if so, your comment > > seems > > to be right. > = > Yes, Quad and Dual modes should be regarded as extension of SPI protocol. > - They follow the same basic principle of synchronous data transfer. Righ= t ? > - These modes are not adding any extra side-band | In-band signaling or > controls to modify the protocol. They are just increasing the width of > data-channel for better throughput. > = > with regards, pekon > = In general, yes. But I think, for the interface we have to take care of mor= e details. For example, what happens in the following situation: We have a spi-controller, which supports the QSPI mode, and a spi-flash, wh= ich fulfils = the requirements, but the board has not connected all signals? And the interface for the slave-driver (like m25p80) should allow to specif= y the transfer mode for each spi_message. This will be necessary, because it depends on the flash and mode, how each = phase of "cmd", "address", and "data" will be transferred. I don't know, if it is only me, but I would like to see some more abstract = description for all = these scenarios, before the details of an interface really could be discuss= ed and decided. Best Regards, Thomas ---------------------------------------------------------------------------= --- See everything from the browser to the database with AppDynamics Get end-to-end visibility with application monitoring from AppDynamics Isolate bottlenecks and diagnose root cause in seconds. Start your free trial of AppDynamics Pro today! http://pubads.g.doubleclick.net/gampad/clk?id=3D48808831&iu=3D/4140/ostg.cl= ktrk From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp1.lantiq.com ([195.219.66.200]) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1Uz2Fq-0007UH-J2 for linux-mtd@lists.infradead.org; Tue, 16 Jul 2013 10:13:11 +0000 From: To: , Subject: RE: support DUAL and QUAD[patch v1] Date: Tue, 16 Jul 2013 10:12:46 +0000 Message-ID: <593AEF6C47F46446852B067021A273D6D93B49E1@MUCSE039.lantiq.com> References: <20980858CB6D3A4BAE95CA194937D5E73E9E84D2@DBDE04.ent.ti.com> <20980858CB6D3A4BAE95CA194937D5E73E9E851E@DBDE04.ent.ti.com> In-Reply-To: <20980858CB6D3A4BAE95CA194937D5E73E9E851E@DBDE04.ent.ti.com> Content-Language: en-US Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Cc: spi-devel-general@lists.sourceforge.net, sourav.poddar@ti.com, broonie@kernel.org, linux-mtd@lists.infradead.org List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hello Pekon, Gupta, Pekon wrote on=A02013-07-16: > > > > Hi, Gupta > > > > > > > [Pekon]: Instead of adding new fields you can use existing 'mode' fie= ld to > > > pass on the platform specific configurations. And if 'u8 mode' does n= ot > > > suffice you can increase it to 'u32'. > > > #define QSPI_MODE 1 << 5; // just check which bit-fields are un= -used > > > spi_board_info->mode |=3D QSPI_MODE; > > > > > > > well, can dual and quad be regarded as a spi mode? if so, your comment > > seems > > to be right. >=20 > Yes, Quad and Dual modes should be regarded as extension of SPI protocol. > - They follow the same basic principle of synchronous data transfer. Righ= t ? > - These modes are not adding any extra side-band | In-band signaling or > controls to modify the protocol. They are just increasing the width of > data-channel for better throughput. >=20 > with regards, pekon >=20 In general, yes. But I think, for the interface we have to take care of mor= e details. For example, what happens in the following situation: We have a spi-controller, which supports the QSPI mode, and a spi-flash, wh= ich fulfils=20 the requirements, but the board has not connected all signals? And the interface for the slave-driver (like m25p80) should allow to specif= y the transfer mode for each spi_message. This will be necessary, because it depends on the flash and mode, how each = phase of "cmd", "address", and "data" will be transferred. I don't know, if it is only me, but I would like to see some more abstract = description for all=20 these scenarios, before the details of an interface really could be discuss= ed and decided. Best Regards, Thomas