Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754093Ab3CKLcx (ORCPT ); Mon, 11 Mar 2013 07:32:53 -0400 Received: from mga09.intel.com ([134.134.136.24]:2336 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753897Ab3CKLcv (ORCPT ); Mon, 11 Mar 2013 07:32:51 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.84,822,1355126400"; d="scan'208";a="299025976" From: "Shevchenko, Andriy" To: linux-kernel , "Koul, Vinod" , Arnd Bergmann CC: Viresh Kumar , Guennadi Liakhovetski , Mika Westerberg Subject: A proposal to check the device in generic way Thread-Topic: A proposal to check the device in generic way Thread-Index: AQHOHkwes8g2THZZt02CceOgK5RzFQ== Date: Mon, 11 Mar 2013 11:32:31 +0000 Message-ID: <1363001537.18714.3.camel@smile> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.237.72.173] Content-Type: text/plain; charset="utf-8" Content-ID: <0B74A1371B575B4FBDE0D763C9FE0F92@intel.com> MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by mail.home.local id r2BBWq4W006819 Content-Length: 2028 Lines: 58 Hello. Currently in linux-next we have the following things: $ git grep -n 'chan->device->dev->driver' drivers/dma/ drivers/dma/amba-pl08x.c:1594: if (chan->device->dev->driver != &pl08x_amba_driver.drv) drivers/dma/dmaengine.c:190: return chan->device->dev->driver->owner; drivers/dma/edma.c:609: if (chan->device->dev->driver == &edma_driver.driver) { drivers/dma/omap-dma.c:654: if (chan->device->dev->driver == &omap_dma_driver.driver) { drivers/dma/pl330.c:2374: if (chan->device->dev->driver != &pl330_driver.drv) drivers/dma/sa11x0-dma.c:1080: if (chan->device->dev->driver == &sa11x0_dma_driver.driver) I think it's a non-generic way to check which driver provides a channel into filter function. First of all, I don't get why that comparison goes as deep as driver structure. Isn't clearer to check chan->device->dev against the struct dev passed in the custom parameter structure? Like: struct filter_params { struct dev *dev; void *param; }; bool filter_fn(struct dma_chan *chan, void *fparams) { struct filter_params *p = fparams; if (chan->device->dev != p->dev) return false; ... } In case my idea has a right to live, what about to move such check inside DMA engine code? Opinions, comments? Earlier I tried to discuss this with Arnd here: http://www.spinics.net/lists/arm-kernel/msg220716.html -- Andy Shevchenko Intel Finland Oy --------------------------------------------------------------------- Intel Finland Oy Registered Address: PL 281, 00181 Helsinki Business Identity Code: 0357606 - 4 Domiciled in Helsinki This e-mail and any attachments may contain confidential material for the sole use of the intended recipient(s). Any review or distribution by others is strictly prohibited. If you are not the intended recipient, please contact the sender and delete all copies. ????{.n?+???????+%?????ݶ??w??{.n?+????{??G?????{ay?ʇڙ?,j??f???h?????????z_??(?階?ݢj"???m??????G????????????&???~???iO???z??v?^?m???? ????????I?