From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shawn Lin Subject: Re: spi: rockchip: check requesting dma channel with EPROBE_DEFER Date: Mon, 14 Mar 2016 18:21:00 +0800 Message-ID: <56E6908C.3060904@rock-chips.com> References: <20160314094844.GA12754@mwanda> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20160314094844.GA12754@mwanda> Sender: linux-spi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Dan Carpenter Cc: shawn.lin-TNX95d0MmH7DzftRWevZcw@public.gmane.org, linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-rockchip-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: linux-rockchip.vger.kernel.org On 2016/3/14 17:48, Dan Carpenter wrote: > Hello Shawn Lin, > > The patch 61cadcf46cfd: "spi: rockchip: check requesting dma channel > with EPROBE_DEFER" from Mar 9, 2016, leads to the following static > checker warning: > > drivers/spi/spi-rockchip.c:742 rockchip_spi_probe() > warn: passing zero to 'PTR_ERR' > > drivers/spi/spi-rockchip.c > 732 > 733 rs->dma_tx.ch = dma_request_slave_channel(rs->dev, "tx"); > 734 if (IS_ERR_OR_NULL(rs->dma_tx.ch)) { > 735 /* Check tx to see if we need defer probing driver */ > 736 if (PTR_ERR(rs->dma_tx.ch) == -EPROBE_DEFER) { > 737 ret = -EPROBE_DEFER; > 738 goto err_get_fifo_len; > > What's going on here? Are we planning to change dma_request_slave_channel() > to return error pointers? Also what about other error pointers besides > EPROBE_DEFER it seems dangerous to leave rs->dma_tx.ch as an error > pointer. We probably eventually try to free it if it's non-NULL. yes, we are plannig to return EPROBE_DEFER/NULL for dma_request_slave_channel to make sure we don't decide the dma cap based on driver probe sequence. No any other error pointer will be returned to the caller > > 739 } > 740 dev_warn(rs->dev, "Failed to request TX DMA channel\n"); > 741 } > 742 > > regards, > dan carpenter > > > -- Best Regards Shawn Lin -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html