From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 898F4C2D0D0 for ; Mon, 23 Dec 2019 15:50:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 577E42073A for ; Mon, 23 Dec 2019 15:50:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1577116208; bh=RMoTjXwZcjIZ4sWdkpbd+CDNN2WUkeQnAYsgLbSVu54=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=odGWOjz59ylnCasUqcJWy7sZpyfY71VCQ8n1QwGJMjQgBDLKn9xUmmhNISBv12Zx1 SR+fEYu83W5uAi/SwKwlR8RYZOE4L9dQsFp86skRi8RTS7R8J2KV9sYJjnuzbRSU9y zqhIkgVl52zoE4uRW+w0RAc0TuqvzWSHqZ0v8rG8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726834AbfLWPuH (ORCPT ); Mon, 23 Dec 2019 10:50:07 -0500 Received: from mail.kernel.org ([198.145.29.99]:46550 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725912AbfLWPuH (ORCPT ); Mon, 23 Dec 2019 10:50:07 -0500 Received: from archlinux (cpc149474-cmbg20-2-0-cust94.5-4.cable.virginm.net [82.4.196.95]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id EBEEE20663; Mon, 23 Dec 2019 15:50:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1577116206; bh=RMoTjXwZcjIZ4sWdkpbd+CDNN2WUkeQnAYsgLbSVu54=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=FDm6HjWvnEvmXVY0d+ZFGhVyJKlxV+7EhJpQtv6xEMM41psUFVFCb57loxIJZgKiJ 8ESQcAoSB6lRrFp44fsrTaQP6YSbeMkKuLIiIstmeTo2dJg78X7g2ywMc2LZiExtCp /Ukdrs/au3+oxV4Rfu/LE4M+uEPDymjU8xXO+It8= Date: Mon, 23 Dec 2019 15:50:01 +0000 From: Jonathan Cameron To: Peter Ujfalusi Cc: , , , , , Subject: Re: [PATCH v2] iio: adc: at91-sama5d2_adc: Use dma_request_chan() instead dma_request_slave_channel() Message-ID: <20191223155001.3c4c7261@archlinux> In-Reply-To: <20191217103100.21737-1-peter.ujfalusi@ti.com> References: <20191217103100.21737-1-peter.ujfalusi@ti.com> X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 17 Dec 2019 12:31:00 +0200 Peter Ujfalusi wrote: > dma_request_slave_channel() is a wrapper on top of dma_request_chan() > eating up the error code. > > By using dma_request_chan() directly the driver can support deferred > probing against DMA. Unfortunately that doesn't seem to be true. The function in question returns void... And for that matter is called only from the set_watermark callback which doesn't run at probe time. So if we were to get a deferred response at runtime there isn't a whole lot we could do with it. Jonathan > > Signed-off-by: Peter Ujfalusi > --- > Hi, > > Changes since v1: > - Subject prefix is corrected to "iio: adc: at91-sama5d2_adc:" > > Regards, > Peter > > drivers/iio/adc/at91-sama5d2_adc.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c > index e1850f3d5cf3..a5c7771227d5 100644 > --- a/drivers/iio/adc/at91-sama5d2_adc.c > +++ b/drivers/iio/adc/at91-sama5d2_adc.c > @@ -1444,10 +1444,10 @@ static void at91_adc_dma_init(struct platform_device *pdev) > if (st->dma_st.dma_chan) > return; > > - st->dma_st.dma_chan = dma_request_slave_channel(&pdev->dev, "rx"); > - > - if (!st->dma_st.dma_chan) { > + st->dma_st.dma_chan = dma_request_chan(&pdev->dev, "rx"); > + if (IS_ERR(st->dma_st.dma_chan)) { > dev_info(&pdev->dev, "can't get DMA channel\n"); > + st->dma_st.dma_chan = NULL; > goto dma_exit; > } >