From: Frank Mori Hess <fmh6jj@gmail.com> To: Vinod Koul <vkoul@kernel.org>, dmaengine@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Dan Williams <dan.j.williams@intel.com>, r.baldyga@hackerion.com Subject: Revert "dmaengine: pl330: add DMA_PAUSE feature" Date: Sat, 28 Apr 2018 17:50:58 -0400 [thread overview] Message-ID: <2484918.HKVQc3yJkt@bear> (raw) This reverts commit 88987d2c7534a0269f567fb101e6d71a08f0f01d. The pl330.c pause implementation violates the dmaengine requirement for no data loss, since it relies on the DMAKILL instruction. However, DMAKILL discards in-flight data from the dma controller's fifo. This is documented in the dma-330 manual and I have observed it with hardware doing device-to-memory burst transfers. The discarded data may or may not show up in the residue count, depending on timing (resulting in data corruption effectively). Signed-off-by: Frank Mori Hess <fmh6jj@gmail.com> --- drivers/dma/pl330.c | 28 ---------------------------- 1 file changed, 28 deletions(-) diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c index 6237069001c4..f802bd3b0481 100644 --- a/drivers/dma/pl330.c +++ b/drivers/dma/pl330.c @@ -2290,33 +2290,6 @@ static int pl330_terminate_all(struct dma_chan *chan) return 0; } -/* - * We don't support DMA_RESUME command because of hardware - * limitations, so after pausing the channel we cannot restore - * it to active state. We have to terminate channel and setup - * DMA transfer again. This pause feature was implemented to - * allow safely read residue before channel termination. - */ -static int pl330_pause(struct dma_chan *chan) -{ - struct dma_pl330_chan *pch = to_pchan(chan); - struct pl330_dmac *pl330 = pch->dmac; - unsigned long flags; - - pm_runtime_get_sync(pl330->ddma.dev); - spin_lock_irqsave(&pch->lock, flags); - - spin_lock(&pl330->lock); - _stop(pch->thread); - spin_unlock(&pl330->lock); - - spin_unlock_irqrestore(&pch->lock, flags); - pm_runtime_mark_last_busy(pl330->ddma.dev); - pm_runtime_put_autosuspend(pl330->ddma.dev); - - return 0; -} - static void pl330_free_chan_resources(struct dma_chan *chan) { struct dma_pl330_chan *pch = to_pchan(chan); @@ -3027,7 +3000,6 @@ pl330_probe(struct amba_device *adev, const struct amba_id *id) pd->device_tx_status = pl330_tx_status; pd->device_prep_slave_sg = pl330_prep_slave_sg; pd->device_config = pl330_config; - pd->device_pause = pl330_pause; pd->device_terminate_all = pl330_terminate_all; pd->device_issue_pending = pl330_issue_pending; pd->src_addr_widths = PL330_DMA_BUSWIDTHS;
WARNING: multiple messages have this Message-ID (diff)
From: Frank Mori Hess <fmh6jj@gmail.com> To: Vinod Koul <vkoul@kernel.org>, dmaengine@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Dan Williams <dan.j.williams@intel.com>, r.baldyga@hackerion.com Subject: [PATCH] Revert "dmaengine: pl330: add DMA_PAUSE feature" Date: Sat, 28 Apr 2018 17:50:58 -0400 [thread overview] Message-ID: <2484918.HKVQc3yJkt@bear> (raw) This reverts commit 88987d2c7534a0269f567fb101e6d71a08f0f01d. The pl330.c pause implementation violates the dmaengine requirement for no data loss, since it relies on the DMAKILL instruction. However, DMAKILL discards in-flight data from the dma controller's fifo. This is documented in the dma-330 manual and I have observed it with hardware doing device-to-memory burst transfers. The discarded data may or may not show up in the residue count, depending on timing (resulting in data corruption effectively). Signed-off-by: Frank Mori Hess <fmh6jj@gmail.com> --- drivers/dma/pl330.c | 28 ---------------------------- 1 file changed, 28 deletions(-) diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c index 6237069001c4..f802bd3b0481 100644 --- a/drivers/dma/pl330.c +++ b/drivers/dma/pl330.c @@ -2290,33 +2290,6 @@ static int pl330_terminate_all(struct dma_chan *chan) return 0; } -/* - * We don't support DMA_RESUME command because of hardware - * limitations, so after pausing the channel we cannot restore - * it to active state. We have to terminate channel and setup - * DMA transfer again. This pause feature was implemented to - * allow safely read residue before channel termination. - */ -static int pl330_pause(struct dma_chan *chan) -{ - struct dma_pl330_chan *pch = to_pchan(chan); - struct pl330_dmac *pl330 = pch->dmac; - unsigned long flags; - - pm_runtime_get_sync(pl330->ddma.dev); - spin_lock_irqsave(&pch->lock, flags); - - spin_lock(&pl330->lock); - _stop(pch->thread); - spin_unlock(&pl330->lock); - - spin_unlock_irqrestore(&pch->lock, flags); - pm_runtime_mark_last_busy(pl330->ddma.dev); - pm_runtime_put_autosuspend(pl330->ddma.dev); - - return 0; -} - static void pl330_free_chan_resources(struct dma_chan *chan) { struct dma_pl330_chan *pch = to_pchan(chan); @@ -3027,7 +3000,6 @@ pl330_probe(struct amba_device *adev, const struct amba_id *id) pd->device_tx_status = pl330_tx_status; pd->device_prep_slave_sg = pl330_prep_slave_sg; pd->device_config = pl330_config; - pd->device_pause = pl330_pause; pd->device_terminate_all = pl330_terminate_all; pd->device_issue_pending = pl330_issue_pending; pd->src_addr_widths = PL330_DMA_BUSWIDTHS; -- 2.11.0
next reply other threads:[~2018-04-28 21:50 UTC|newest] Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-04-28 21:50 Frank Mori Hess [this message] 2018-04-28 21:50 ` [PATCH] Revert "dmaengine: pl330: add DMA_PAUSE feature" Frank Mori Hess 2018-05-02 4:32 Vinod Koul 2018-05-02 4:32 ` [PATCH] " Vinod Koul 2018-05-02 14:37 Frank Mori Hess 2018-05-02 14:37 ` [PATCH] " Frank Mori Hess 2018-05-03 9:01 Vinod Koul 2018-05-03 9:01 ` [PATCH] " Vinod Koul 2018-05-03 16:35 Vinod Koul 2018-05-03 16:35 ` [PATCH] " Vinod Koul 2018-05-08 9:04 Marek Szyprowski 2018-05-08 9:04 ` Marek Szyprowski 2018-05-08 14:36 Frank Mori Hess 2018-05-08 14:36 ` Frank Mori Hess 2018-05-09 6:59 Vinod Koul 2018-05-09 6:59 ` Vinod Koul 2018-05-09 13:19 Marek Szyprowski 2018-05-09 13:19 ` Marek Szyprowski 2018-05-09 17:48 Frank Mori Hess 2018-05-09 17:48 ` Frank Mori Hess 2018-05-10 8:31 Marek Szyprowski 2018-05-10 8:31 ` Marek Szyprowski 2018-05-10 16:04 Frank Mori Hess 2018-05-10 16:04 ` Frank Mori Hess 2018-05-11 12:57 Marek Szyprowski 2018-05-11 12:57 ` Marek Szyprowski 2018-05-11 15:57 Frank Mori Hess 2018-05-11 15:57 ` Frank Mori Hess 2018-05-15 6:21 Vinod Koul 2018-05-15 6:21 ` Vinod 2018-05-15 12:24 Marek Szyprowski 2018-05-15 12:24 ` Marek Szyprowski 2018-05-15 13:45 Vinod Koul 2018-05-15 13:45 ` Vinod 2018-05-15 15:50 Frank Mori Hess 2018-05-15 15:50 ` Frank Mori Hess 2018-05-17 4:19 Vinod Koul 2018-05-17 4:19 ` Vinod Koul 2018-05-17 16:20 Frank Mori Hess 2018-05-17 16:20 ` Frank Mori Hess 2018-05-17 17:22 Lars-Peter Clausen 2018-05-17 17:22 ` Lars-Peter Clausen 2018-05-18 4:03 Vinod Koul 2018-05-18 4:03 ` Vinod 2018-05-18 6:28 Marek Szyprowski 2018-05-18 6:28 ` Marek Szyprowski 2018-05-18 7:21 Vinod Koul 2018-05-18 7:21 ` Vinod 2018-05-18 18:56 Frank Mori Hess 2018-05-18 18:56 ` Frank Mori Hess 2018-05-18 19:01 Frank Mori Hess 2018-05-18 19:01 ` Frank Mori Hess 2018-05-21 9:16 Vinod Koul 2018-05-21 9:16 ` Vinod Koul 2018-05-22 0:56 Frank Mori Hess 2018-05-22 0:56 ` Frank Mori Hess 2018-05-22 3:37 Vinod Koul 2018-05-22 3:37 ` Vinod Koul 2018-05-22 14:27 Frank Mori Hess 2018-05-22 14:27 ` Frank Mori Hess 2018-05-23 5:39 Vinod Koul 2018-05-23 5:39 ` Vinod 2018-05-29 5:17 Marek Szyprowski 2018-05-29 5:17 ` Marek Szyprowski 2018-05-29 7:09 Vinod Koul 2018-05-29 7:09 ` Vinod
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