+Wolfram Sang >-----Original Message----- >From: linux-arm-kernel [mailto:linux-arm-kernel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Sricharan R >Sent: Friday, June 10, 2016 11:38 PM >To: linux-arm-msm@xxxxxxxxxxxxxxx; ntelkar@xxxxxxxxxxxxxx; galak@xxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; >andy.gross@xxxxxxxxxx; linux-i2c@xxxxxxxxxxxxxxx; agross@xxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; >nkaje@xxxxxxxxxxxxxx; absahu@xxxxxxxxxxxxxx >Cc: sricharan@xxxxxxxxxxxxxx >Subject: [PATCH V4 1/3] i2c: qup: Fix broken dma when CONFIG_DEBUG_SG is enabled > >With CONFIG_DEBUG_SG is enabled and when dma mode is used, below dump is seen, > >------------[ cut here ]------------ >kernel BUG at include/linux/scatterlist.h:140! >Internal error: Oops - BUG: 0 [#1] PREEMPT SMP >Modules linked in: >CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.4.0-00459-g9f087b9-dirty #7 >Hardware name: Qualcomm Technologies, Inc. APQ 8016 SBC (DT) >task: ffffffc036868000 ti: ffffffc036870000 task.ti: ffffffc036870000 >PC is at qup_sg_set_buf.isra.13+0x138/0x154 >LR is at qup_sg_set_buf.isra.13+0x50/0x154 >pc : [<ffffffc0005a0ed8>] lr : [<ffffffc0005a0df0>] pstate: 60000145 >sp : ffffffc0368735c0 >x29: ffffffc0368735c0 x28: ffffffc036873752 >x27: ffffffc035233018 x26: ffffffc000c4e000 >x25: 0000000000000000 x24: 0000000000000004 >x23: 0000000000000000 x22: ffffffc035233668 >x21: ffffff80004e3000 x20: ffffffc0352e0018 >x19: 0000004000000000 x18: 0000000000000028 >x17: 0000000000000004 x16: ffffffc0017a39c8 >x15: 0000000000001cdf x14: ffffffc0019929d8 >x13: ffffffc0352e0018 x12: 0000000000000000 >x11: 0000000000000001 x10: 0000000000000001 >x9 : ffffffc0012b2d70 x8 : ffffff80004e3000 >x7 : 0000000000000018 x6 : 0000000030000000 >x5 : ffffffc00199f018 x4 : ffffffc035233018 >x3 : 0000000000000004 x2 : 00000000c0000000 >x1 : 0000000000000003 x0 : 0000000000000000 > >Process swapper/0 (pid: 1, stack limit = 0xffffffc036870020) >Stack: (0xffffffc0368735c0 to 0xffffffc036874000) > >sg_set_bug expects that the buf parameter passed in should be from >lowmem and a valid pageframe. This is not true for pages from >dma_alloc_coherent which can be carveouts, hence the check fails. >Change allocation of sg buffers from dma_coherent memory to kzalloc >to fix the issue. Note that now dma_map/unmap is used to make the >kzalloc'ed buffers coherent before passing it to the dmaengine. > >Signed-off-by: Sricharan R <sricharan@xxxxxxxxxxxxxx> >Reviewed-by: Andy Gross <andy.gross@xxxxxxxxxx> >--- > drivers/i2c/busses/i2c-qup.c | 51 +++++++++++++------------------------------- > 1 file changed, 15 insertions(+), 36 deletions(-) > >diff --git a/drivers/i2c/busses/i2c-qup.c b/drivers/i2c/busses/i2c-qup.c >index cc6439ab..43adc2d 100644 >--- a/drivers/i2c/busses/i2c-qup.c >+++ b/drivers/i2c/busses/i2c-qup.c >@@ -585,8 +585,8 @@ static void qup_i2c_bam_cb(void *data) > } > > static int qup_sg_set_buf(struct scatterlist *sg, void *buf, >- struct qup_i2c_tag *tg, unsigned int buflen, >- struct qup_i2c_dev *qup, int map, int dir) >+ unsigned int buflen, struct qup_i2c_dev *qup, >+ int dir) > { > int ret; > >@@ -595,9 +595,6 @@ static int qup_sg_set_buf(struct scatterlist *sg, void *buf, > if (!ret) > return -EINVAL; > >- if (!map) >- sg_dma_address(sg) = tg->addr + ((u8 *)buf - tg->start); >- > return 0; > } > >@@ -670,16 +667,15 @@ static int qup_i2c_bam_do_xfer(struct qup_i2c_dev *qup, struct i2c_msg *msg, > /* scratch buf to read the start and len tags */ > ret = qup_sg_set_buf(&qup->brx.sg[rx_buf++], > &qup->brx.tag.start[0], >- &qup->brx.tag, >- 2, qup, 0, 0); >+ 2, qup, DMA_FROM_DEVICE); > > if (ret) > return ret; > > ret = qup_sg_set_buf(&qup->brx.sg[rx_buf++], > &msg->buf[limit * i], >- NULL, tlen, qup, >- 1, DMA_FROM_DEVICE); >+ tlen, qup, >+ DMA_FROM_DEVICE); > if (ret) > return ret; > >@@ -688,7 +684,7 @@ static int qup_i2c_bam_do_xfer(struct qup_i2c_dev *qup, struct i2c_msg *msg, > } > ret = qup_sg_set_buf(&qup->btx.sg[tx_buf++], > &qup->start_tag.start[off], >- &qup->start_tag, len, qup, 0, 0); >+ len, qup, DMA_TO_DEVICE); > if (ret) > return ret; > >@@ -696,8 +692,7 @@ static int qup_i2c_bam_do_xfer(struct qup_i2c_dev *qup, struct i2c_msg *msg, > /* scratch buf to read the BAM EOT and FLUSH tags */ > ret = qup_sg_set_buf(&qup->brx.sg[rx_buf++], > &qup->brx.tag.start[0], >- &qup->brx.tag, 2, >- qup, 0, 0); >+ 2, qup, DMA_FROM_DEVICE); > if (ret) > return ret; > } else { >@@ -709,17 +704,15 @@ static int qup_i2c_bam_do_xfer(struct qup_i2c_dev *qup, struct i2c_msg *msg, > len = qup_i2c_set_tags(tags, qup, msg, 1); > > ret = qup_sg_set_buf(&qup->btx.sg[tx_buf++], >- tags, >- &qup->start_tag, len, >- qup, 0, 0); >+ tags, len, >+ qup, DMA_TO_DEVICE); > if (ret) > return ret; > > tx_len += len; > ret = qup_sg_set_buf(&qup->btx.sg[tx_buf++], > &msg->buf[limit * i], >- NULL, tlen, qup, 1, >- DMA_TO_DEVICE); >+ tlen, qup, DMA_TO_DEVICE); > if (ret) > return ret; > i++; >@@ -738,8 +731,7 @@ static int qup_i2c_bam_do_xfer(struct qup_i2c_dev *qup, struct i2c_msg *msg, > QUP_BAM_FLUSH_STOP; > ret = qup_sg_set_buf(&qup->btx.sg[tx_buf++], > &qup->btx.tag.start[0], >- &qup->btx.tag, len, >- qup, 0, 0); >+ len, qup, DMA_TO_DEVICE); > if (ret) > return ret; > tx_nents += 1; >@@ -1407,27 +1399,21 @@ static int qup_i2c_probe(struct platform_device *pdev) > > /* 2 tag bytes for each block + 5 for start, stop tags */ > size = blocks * 2 + 5; >- qup->dpool = dma_pool_create("qup_i2c-dma-pool", &pdev->dev, >- size, 4, 0); > >- qup->start_tag.start = dma_pool_alloc(qup->dpool, GFP_KERNEL, >- &qup->start_tag.addr); >+ qup->start_tag.start = devm_kzalloc(&pdev->dev, >+ size, GFP_KERNEL); > if (!qup->start_tag.start) { > ret = -ENOMEM; > goto fail_dma; > } > >- qup->brx.tag.start = dma_pool_alloc(qup->dpool, >- GFP_KERNEL, >- &qup->brx.tag.addr); >+ qup->brx.tag.start = devm_kzalloc(&pdev->dev, 2, GFP_KERNEL); > if (!qup->brx.tag.start) { > ret = -ENOMEM; > goto fail_dma; > } > >- qup->btx.tag.start = dma_pool_alloc(qup->dpool, >- GFP_KERNEL, >- &qup->btx.tag.addr); >+ qup->btx.tag.start = devm_kzalloc(&pdev->dev, 2, GFP_KERNEL); > if (!qup->btx.tag.start) { > ret = -ENOMEM; > goto fail_dma; >@@ -1566,13 +1552,6 @@ static int qup_i2c_remove(struct platform_device *pdev) > struct qup_i2c_dev *qup = platform_get_drvdata(pdev); > > if (qup->is_dma) { >- dma_pool_free(qup->dpool, qup->start_tag.start, >- qup->start_tag.addr); >- dma_pool_free(qup->dpool, qup->brx.tag.start, >- qup->brx.tag.addr); >- dma_pool_free(qup->dpool, qup->btx.tag.start, >- qup->btx.tag.addr); >- dma_pool_destroy(qup->dpool); > dma_release_channel(qup->btx.dma); > dma_release_channel(qup->brx.dma); > } >-- >QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux >Foundation > > >_______________________________________________ >linux-arm-kernel mailing list >linux-arm-kernel@xxxxxxxxxxxxxxxxxxx >http://lists.infradead.org/mailman/listinfo/linux-arm-kernel -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
