From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Brownell Subject: Re: [PATCH - Omapzoom] [NAND] Add prefetch and DMA support Date: Mon, 8 Sep 2008 15:27:35 -0700 Message-ID: <200809081527.35446.david-b@pacbell.net> References: Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from smtp120.sbc.mail.sp1.yahoo.com ([69.147.64.93]:41648 "HELO smtp120.sbc.mail.sp1.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1753522AbYIHW1h (ORCPT ); Mon, 8 Sep 2008 18:27:37 -0400 In-Reply-To: Content-Disposition: inline Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: "Kamat, Nishant" Cc: "Pandita, Vikram" , "linux-omap@vger.kernel.org" , "Singh, Vimal" On Monday 08 September 2008, Kamat, Nishant wrote: > +config MTD_NAND_OMAP_PREFETCH > + =A0 =A0 =A0 bool "GPMC prefetch support for NAND Flash device" > + =A0 =A0 =A0 depends on MTD_NAND && MTD_NAND_OMAP2 > + =A0 =A0 =A0 default n > + =A0 =A0 =A0 help > + =A0 =A0 =A0 =A0The NAND device can be accessed for Read/Write using= GPMC PREFETCH engine > + =A0 =A0 =A0 =A0to improve the performance. Is there a reason this isn't always enabled, and the choice is just whether to use DMA or not? I'd be interested to see performance measurements for the three cases. - current/slow code - the readsw() update I sent previously - this "prefetch engine" And I'd expect this "prefetch engine" code would also be improved by using readsw() and writesw() when DMA isn't in use. On one ARM926 I observed a 16% speedup *just* from switching from slow byte-at-a-time PIO to using readsb ... this current code has that same pessimization. - Dave > + > +choice > + =A0 =A0 =A0 prompt "Prefetch engine support for GPMC" > + =A0 =A0 =A0 depends on MTD_NAND_OMAP_PREFETCH > + =A0 =A0 =A0 help > + =A0 =A0 =A0 =A0The GPMC PREFETCH engine can be configured eigther i= n MPU interrupt mode > + =A0 =A0 =A0 =A0or in DMA interrupt mode. > + > +config MTD_NAND_OMAP_PREFETCH_MPU > + =A0 =A0 =A0 depends on MTD_NAND_OMAP_PREFETCH > + =A0 =A0 =A0 bool "MPU mode always for spare area + MPU mode for mai= n area" > + =A0 =A0 =A0 help > + =A0 =A0 =A0 =A0Say y if... you want MPU interrupt mode for both spa= re area and main area accesses. > + > +config MTD_NAND_OMAP_PREFETCH_DMA > + =A0 =A0 =A0 depends on MTD_NAND_OMAP_PREFETCH > + =A0 =A0 =A0 bool "MPU mode always for spare area + DMA mode for mai= n area" > + =A0 =A0 =A0 help > + =A0 =A0 =A0 =A0Say y if... you want MPU interrupt mode for spare ar= ea and DMA mode for main > + =A0 =A0 =A0 =A0area access. > + > +endchoice > + -- To unsubscribe from this list: send the line "unsubscribe linux-omap" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html