Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932692Ab1EYUrS (ORCPT ); Wed, 25 May 2011 16:47:18 -0400 Received: from mail-iw0-f174.google.com ([209.85.214.174]:61703 "EHLO mail-iw0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932237Ab1EYUrP (ORCPT ); Wed, 25 May 2011 16:47:15 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type; b=FDsKU+MSAdlEWaVSGeJfyFFOVqKfE+8IjWdriy2jo+JtZJEWd6T/pCR0tWAsJ3oYHI WWANBXBUN4UzAwQdfsmwj/FLxI5iQMbW7dDZFj0/tzdj1HFZYC07SbUrkfQXkxKK/r+0 T7z0H15iSPXQ+i776DXuSswKJrmEwBTVQS77o= MIME-Version: 1.0 In-Reply-To: <20110525195413.GC2996@acer> References: <20110525195413.GC2996@acer> Date: Wed, 25 May 2011 22:47:14 +0200 X-Google-Sender-Auth: kZ-7G7Mw8h3x2E4QSqmblxpkXsc Message-ID: Subject: Re: [PATCH 1/5] dmaengine: add ep93xx DMA support From: Linus Walleij To: Mika Westerberg Cc: linux-arm-kernel@lists.infradead.org, Vinod Koul , linux-kernel@vger.kernel.org, hsweeten@visionengravers.com, ryan@bluewatersys.com, Dan Williams , Grant Likely , spi mailing list Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1894 Lines: 43 2011/5/25 Mika Westerberg : > I re-checked the specs and indeed, as discussed previously, it is clear that > Cirrus (or ARM) copied the interface from other. Even the wording in the > document is identical in many places. However, in ep93xx User's Guide, there > is no mention about SSP being AMBA PrimeCell peripheral. For UARTs it is > mentioned... go figure. > > There are differences also, some of the bits in control registers are in > different places. Interrupt registers are completely different and there is no > DMA control register at all. The same things we discussed before. But it really does not matter. The amba-pl022.c driver has all the same deviations for things called "PL023" that are not pure PL022 either. I just made the driver a bit more flexible, supporting both. If the people doing drivers/usb/musb/* had done the same thing we would have had what, 5 drivers for similar hardware? > Back then, it wasn't known how the M2M DMA interface (the one used > by SSP and IDE) was going to be implemented. But I knew, having just written the needed extensions to dmaengine. And I said so. But I realize I'm maybe not considered an authoritative source on the subject, and I'm biased. > IMHO it is better to have ep93xx implementation on its own driver since it is > not a real AMBA PL022 peripheral but some weird hack made by Cirrus (although > my opinions are bit biased). I disagree because it's IMO at first sight no more deviant than our "PL023" variants that still use the same pl022 driver. Is there some inexepensive hardware with EP93xx I can get to fix this myself? Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/