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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A8327ECAAD8 for ; Tue, 20 Sep 2022 10:08:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:From:References:Cc:To:Subject: MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=x3vjrnOO1TlDleeqYub7TL+LVo0B30f8jIS4DHbZMEM=; b=rC8Gewm/uCKi15 rFt72cRLp6ZXC+6A+EG29E7z/agzai1+sk/ObI9xKCRDchAJ0+PFUpXWRfyrroHAApqc44saThtcF 2OuHd3NYL9uJfc31PtBq2k1XbAhmaj5SGh2B8Y8BDjctY3Ak420DFR25+YRLgY3IOU90PO09f5dN5 3WlCw7gdYyYb2kjfKi/OlUYZnvr7/BXhbhKyXO5tQ0FFFKBTG5wwW6DvMCleGRfjv/g/GBsyX8sDl cLizXFf7+wCUsn98fZhuQB8cEY6YbDVFPhSX8M4Iu+k//TDCSol1W2/ywDkODKke0rI1Kd3LNH2Qp oI0fF9KFI/nHyFJRkkyg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oaa9w-002lTM-MB; Tue, 20 Sep 2022 10:07:20 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oaa9r-002lMh-FS for linux-arm-kernel@lists.infradead.org; Tue, 20 Sep 2022 10:07:17 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 6FCC4169C; Tue, 20 Sep 2022 03:07:16 -0700 (PDT) Received: from [10.57.18.118] (unknown [10.57.18.118]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 53F333F73B; Tue, 20 Sep 2022 03:07:07 -0700 (PDT) Message-ID: <5ef51421-e6b0-edd5-6b6e-439b47b794a8@arm.com> Date: Tue, 20 Sep 2022 11:07:05 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:102.0) Gecko/20100101 Thunderbird/102.2.2 Subject: Re: [BUG] ls1046a: eDMA does not transfer data from I2C Content-Language: en-GB To: Sean Anderson , Oleksij Rempel , Pengutronix Kernel Team , linux-i2c@vger.kernel.org, linux-arm-kernel , Vinod Koul , dmaengine@vger.kernel.org Cc: Li Yang , Peng Ma , Linux Kernel Mailing List , dri-devel@lists.freedesktop.org, =?UTF-8?Q?Christian_K=c3=b6nig?= , linaro-mm-sig@lists.linaro.org, Robin Gong , Shawn Guo , Sumit Semwal , Joy Zou , linux-media@vger.kernel.org References: <38974aab-06d0-f5ff-d359-5eedd2f3bb3e@seco.com> From: Robin Murphy In-Reply-To: <38974aab-06d0-f5ff-d359-5eedd2f3bb3e@seco.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220920_030715_675067_F0A531F7 X-CRM114-Status: GOOD ( 20.05 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2022-09-19 23:24, Sean Anderson wrote: > Hi all, > > I discovered a bug in either imx_i2c or fsl-edma on the LS1046A where no > data is read in i2c_imx_dma_read except for the last two bytes (which > are not read using DMA). This is perhaps best illustrated with the > following example: > > # hexdump -C /sys/bus/nvmem/devices/0-00540/nvmem > [ 308.914884] i2c i2c-0: ffff000809380000 0x0000000889380000 0x00000000f5401000 ffff000075401000 > [ 308.923529] src= 2180004 dst=f5401000 attr= 0 soff= 0 nbytes=1 slast= 0 > [ 308.923529] citer= 7e biter= 7e doff= 1 dlast_sga= 0 > [ 308.923529] major_int=1 disable_req=1 enable_sg=0 > [ 308.942113] fsl-edma 2c00000.edma: vchan 000000001b4371fc: txd 00000000d9dd26c5[4]: submitted > [ 308.974049] fsl-edma 2c00000.edma: txd 00000000d9dd26c5[4]: marked complete > [ 308.981339] i2c i2c-0: ffff000809380000 = [2e 2e 2f 2e 2e 2f 2e 2e 2f 64 65 76 69 63 65 73 2f 70 6c 61 74 66 6f 72 6d 2f 73 6f 63 2f 32 31 38 30 30 30 30 2e 69 32 63 2f 69 32 63 2d 30 2f 30 2d 30 30 35 34 2f 30 2d 30 30 35 34 30 00 00] > [ 309.002226] i2c i2c-0: ffff000075401000 = [2e 2e 2f 2e 2e 2f 2e 2e 2f 64 65 76 69 63 65 73 2f 70 6c 61 74 66 6f 72 6d 2f 73 6f 63 2f 32 31 38 30 30 30 30 2e 69 32 63 2f 69 32 63 2d 30 2f 30 2d 30 30 35 34 2f 30 2d 30 30 35 34 30 00 00] > [ 309.024649] i2c i2c-0: ffff000809380080 0x0000000889380080 0x00000000f5401800 ffff000075401800 > [ 309.033270] src= 2180004 dst=f5401800 attr= 0 soff= 0 nbytes=1 slast= 0 > [ 309.033270] citer= 7e biter= 7e doff= 1 dlast_sga= 0 > [ 309.033270] major_int=1 disable_req=1 enable_sg=0 > [ 309.051633] fsl-edma 2c00000.edma: vchan 000000001b4371fc: txd 00000000d9dd26c5[5]: submitted > [ 309.083526] fsl-edma 2c00000.edma: txd 00000000d9dd26c5[5]: marked complete > [ 309.090807] i2c i2c-0: ffff000809380080 = [00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00] > [ 309.111694] i2c i2c-0: ffff000075401800 = [00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00] > 00000000 2e 2e 2f 2e 2e 2f 2e 2e 2f 64 65 76 69 63 65 73 |../../../devices| > 00000010 2f 70 6c 61 74 66 6f 72 6d 2f 73 6f 63 2f 32 31 |/platform/soc/21| > 00000020 38 30 30 30 30 2e 69 32 63 2f 69 32 63 2d 30 2f |80000.i2c/i2c-0/| > 00000030 30 2d 30 30 35 34 2f 30 2d 30 30 35 34 30 00 00 |0-0054/0-00540..| > 00000040 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| > * > 00000070 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff ff |................| > 00000080 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| > * > 000000f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff 5b |...............[| > 00000100 > > (patch with my debug prints appended below) > > Despite the DMA completing successfully, no data was copied into the > buffer, leaving the original (now junk) contents. I probed the I2C bus > with an oscilloscope, and I verified that the transfer did indeed occur. > The timing between submission and completion seems reasonable for the > bus speed (50 kHz for whatever reason). > > I had a look over the I2C driver, and nothing looked obviously > incorrect. If anyone has ideas on what to try, I'm more than willing. Is the DMA controller cache-coherent? I see the mainline LS1046A DT doesn't have a "dma-coherent" property for it, but the behaviour is entirely consistent with that being wrong - dma_map_single() cleans the cache, coherent DMA write hits the still-present cache lines, dma_unmap_single() invalidates the cache, and boom, the data is gone and you read back the previous content of the buffer that was cleaned out to DRAM beforehand. Robin. > --Sean > > diff --git a/drivers/dma/fsl-edma-common.c b/drivers/dma/fsl-edma-common.c > index 15896e2413c4..1d9d4a55d2af 100644 > --- a/drivers/dma/fsl-edma-common.c > +++ b/drivers/dma/fsl-edma-common.c > @@ -391,6 +391,12 @@ void fsl_edma_fill_tcd(struct fsl_edma_hw_tcd *tcd, u32 src, u32 dst, > { > u16 csr = 0; > > + pr_info("src=%8x dst=%8x attr=%4x soff=%4x nbytes=%u slast=%8x\n" > + "citer=%4x biter=%4x doff=%4x dlast_sga=%8x\n" > + "major_int=%d disable_req=%d enable_sg=%d\n", > + src, dst, attr, soff, nbytes, slast, citer, biter, doff, > + dlast_sga, major_int, disable_req, enable_sg); > + > /* > * eDMA hardware SGs require the TCDs to be stored in little > * endian format irrespective of the register endian model. > diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c > index 3576b63a6c03..0217f0cb1331 100644 > --- a/drivers/i2c/busses/i2c-imx.c > +++ b/drivers/i2c/busses/i2c-imx.c > @@ -402,6 +402,9 @@ static int i2c_imx_dma_xfer(struct imx_i2c_struct *i2c_imx, > dev_err(dev, "DMA mapping failed\n"); > goto err_map; > } > + phys_addr_t bufp = virt_to_phys(msgs->buf); > + dev_info(dev, "%px %pap %pad %px\n", msgs->buf, &bufp, > + &dma->dma_buf, phys_to_virt(dma->dma_buf)); > > txdesc = dmaengine_prep_slave_single(dma->chan_using, dma->dma_buf, > dma->dma_len, dma->dma_transfer_dir, > @@ -965,6 +968,9 @@ static int i2c_imx_dma_read(struct imx_i2c_struct *i2c_imx, > } > schedule(); > } > + dev_info(dev, "%px = [%*ph]\n", msgs->buf, msgs->len, msgs->buf); > + dev_info(dev, "%px = [%*ph]\n", phys_to_virt(dma->dma_buf), msgs->len, > + phys_to_virt(dma->dma_buf)); > > temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); > temp &= ~I2CR_DMAEN; _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel