From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759397AbdEWH6K (ORCPT ); Tue, 23 May 2017 03:58:10 -0400 Received: from mail-qt0-f181.google.com ([209.85.216.181]:36020 "EHLO mail-qt0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752619AbdEWH6I (ORCPT ); Tue, 23 May 2017 03:58:08 -0400 MIME-Version: 1.0 In-Reply-To: References: From: Ulf Hansson Date: Tue, 23 May 2017 09:58:07 +0200 Message-ID: Subject: Re: [PATCH] mmc: spi: disable dma mapping code, as it does not work To: Phil Elwell Cc: Martin Sperl , Heiner Kallweit , "linux-mmc@vger.kernel.org" , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 22 May 2017 at 11:09, Phil Elwell wrote: > since: > commit 0589342c27944e50ebd7a54f5215002b6598b748 > Author: Rob Herring > Date: Tue Oct 29 23:36:46 2013 -0500 > > of: set dma_mask to point to coherent_dma_mask > > Platform devices created by DT code don't initialize dma_mask pointer to > anything. Set it to coherent_dma_mask by default if the architecture > code has not set it. > > the mmc-spi driver no longer detects the sd-cards any longer. > > This patch disables the offending section in mmc_spi > so that the driver works again and detects the sd card normally. > > There is no real negative impact as the spi-framework > does no longer rely on driver-provided DMA mappings but > maps the transfers transparently. > > Signed-off-by: Martin Sperl > Submitted-by: Phil Elwell > --- > drivers/mmc/host/mmc_spi.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/drivers/mmc/host/mmc_spi.c b/drivers/mmc/host/mmc_spi.c > index ae19d83bb9de0..16946e2513afa 100644 > --- a/drivers/mmc/host/mmc_spi.c > +++ b/drivers/mmc/host/mmc_spi.c > @@ -1387,6 +1387,16 @@ static int mmc_spi_probe(struct spi_device *spi) > if (!host->data) > goto fail_nobuf1; > > + /* for some reason mmc_spi does not work with this enabled > + * it is not needed anyway, as the SPI framework does DMA > + * transfers now automatically > + * the patch that introduced this was: > + * commit 0589342c27944e50ebd7a54f5215002b6598b748 > + * Author: Rob Herring > + * Date: Tue Oct 29 23:36:46 2013 -0500 > + * of: set dma_mask to point to coherent_dma_mask > + */ > +#if 0 > if (spi->master->dev.parent->dma_mask) { > struct device *dev = spi->master->dev.parent; > > @@ -1402,6 +1412,7 @@ static int mmc_spi_probe(struct spi_device *spi) > host->data_dma, sizeof(*host->data), > DMA_BIDIRECTIONAL); > } > +#endif > > /* setup message for status/busy readback */ > spi_message_init(&host->readback); Phil, I am not sure how to go with this. Your change drops the dma implementation in the mmc_spi driver as host->dma_dev now never gets assigned. I do think that makes sense as the dma support should be implemented in the spi master driver and not in the spi client driver, which currently is the case for mmc_spi. Then perhaps a more proper change would be to remove the dma implementation in mmc_spi altogether? And one more thing, next time also cc the spi-list and Mark Brown, to try to some broader input. Kind regards Uffe