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Wed, 16 Oct 2024 14:40:22 +0200 From: Amelie Delaunay Date: Wed, 16 Oct 2024 14:39:55 +0200 Subject: [PATCH v3 3/9] dmaengine: stm32-dma3: refactor HW linked-list to optimize memory accesses MIME-Version: 1.0 Message-ID: <20241016-dma3-mp25-updates-v3-3-8311fe6f228d@foss.st.com> References: <20241016-dma3-mp25-updates-v3-0-8311fe6f228d@foss.st.com> In-Reply-To: <20241016-dma3-mp25-updates-v3-0-8311fe6f228d@foss.st.com> To: Vinod Koul , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Maxime Coquelin , Alexandre Torgue CC: , , , , , Amelie Delaunay X-Mailer: b4 0.14.2 X-Originating-IP: [10.252.17.239] X-ClientProxiedBy: EQNCAS1NODE4.st.com (10.75.129.82) To SHFDAG1NODE3.st.com (10.75.129.71) X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1039,Hydra:6.0.680,FMLib:17.12.60.29 definitions=2024-09-06_09,2024-09-06_01,2024-09-02_01 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241016_134259_129305_821F5A2D X-CRM114-Status: GOOD ( 15.98 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Current behavior splits the buffer/sg in n * STM32_DMA3_MAX_BLOCK_SIZE + 1 for the remainder without optimization. New behavior splits the buffer/sg in n * STM32_DMA3_MAX_BLOCK_SIZE + 1 for (x * chan->max_burst) + 1 for the remainder. Depending on channel FIFO size, optimal double-word (word if only 8-byte FIFO size) bursts can be programmed before managing the very last remainder with lower data width. In case of _prep_slave_sg, and depending on the channel Transfer Complete event configuration, the user is warned about the refactored linked-list, not having the same items count than the initial sg_list. This warning is shown only if the configuration is successful. Signed-off-by: Amelie Delaunay --- drivers/dma/stm32/stm32-dma3.c | 40 +++++++++++++++++++++++++++++++++------- 1 file changed, 33 insertions(+), 7 deletions(-) diff --git a/drivers/dma/stm32/stm32-dma3.c b/drivers/dma/stm32/stm32-dma3.c index f793eecd2c27ca17cedd5cabbaa1b1beca202039..1d961f5935f935e3855467318cdcde6e6173e43c 100644 --- a/drivers/dma/stm32/stm32-dma3.c +++ b/drivers/dma/stm32/stm32-dma3.c @@ -1126,6 +1126,25 @@ static void stm32_dma3_free_chan_resources(struct dma_chan *c) chan->config_set = 0; } +static u32 stm32_dma3_get_ll_count(struct stm32_dma3_chan *chan, size_t len) +{ + u32 count; + + count = len / STM32_DMA3_MAX_BLOCK_SIZE; + len -= (len / STM32_DMA3_MAX_BLOCK_SIZE) * STM32_DMA3_MAX_BLOCK_SIZE; + + if (len >= chan->max_burst) { + count += 1; /* len < STM32_DMA3_MAX_BLOCK_SIZE here, so it fits in one item */ + len -= (len / chan->max_burst) * chan->max_burst; + } + + /* Unaligned remainder fits in one extra item */ + if (len > 0) + count += 1; + + return count; +} + static void stm32_dma3_init_chan_config_for_memcpy(struct stm32_dma3_chan *chan, dma_addr_t dst, dma_addr_t src) { @@ -1161,7 +1180,7 @@ static struct dma_async_tx_descriptor *stm32_dma3_prep_dma_memcpy(struct dma_cha size_t next_size, offset; u32 count, i, ctr1, ctr2; - count = DIV_ROUND_UP(len, STM32_DMA3_MAX_BLOCK_SIZE); + count = stm32_dma3_get_ll_count(chan, len); swdesc = stm32_dma3_chan_desc_alloc(chan, count); if (!swdesc) @@ -1177,6 +1196,9 @@ static struct dma_async_tx_descriptor *stm32_dma3_prep_dma_memcpy(struct dma_cha remaining = len - offset; next_size = min_t(size_t, remaining, STM32_DMA3_MAX_BLOCK_SIZE); + if (next_size < STM32_DMA3_MAX_BLOCK_SIZE && next_size >= chan->max_burst) + next_size = chan->max_burst * (remaining / chan->max_burst); + ret = stm32_dma3_chan_prep_hw(chan, DMA_MEM_TO_MEM, &swdesc->ccr, &ctr1, &ctr2, src + offset, dst + offset, next_size); if (ret) @@ -1215,12 +1237,9 @@ static struct dma_async_tx_descriptor *stm32_dma3_prep_slave_sg(struct dma_chan u32 i, j, count, ctr1, ctr2; int ret; - count = sg_len; - for_each_sg(sgl, sg, sg_len, i) { - len = sg_dma_len(sg); - if (len > STM32_DMA3_MAX_BLOCK_SIZE) - count += DIV_ROUND_UP(len, STM32_DMA3_MAX_BLOCK_SIZE) - 1; - } + count = 0; + for_each_sg(sgl, sg, sg_len, i) + count += stm32_dma3_get_ll_count(chan, sg_dma_len(sg)); swdesc = stm32_dma3_chan_desc_alloc(chan, count); if (!swdesc) @@ -1237,6 +1256,9 @@ static struct dma_async_tx_descriptor *stm32_dma3_prep_slave_sg(struct dma_chan do { size_t chunk = min_t(size_t, len, STM32_DMA3_MAX_BLOCK_SIZE); + if (chunk < STM32_DMA3_MAX_BLOCK_SIZE && chunk >= chan->max_burst) + chunk = chan->max_burst * (len / chan->max_burst); + if (dir == DMA_MEM_TO_DEV) { src = sg_addr; dst = dev_addr; @@ -1269,6 +1291,10 @@ static struct dma_async_tx_descriptor *stm32_dma3_prep_slave_sg(struct dma_chan } while (len); } + if (count != sg_len && chan->tcem != CTR2_TCEM_CHANNEL) + dev_warn(chan2dev(chan), "Linked-list refactored, %d items instead of %d\n", + count, sg_len); + /* Enable Error interrupts */ swdesc->ccr |= CCR_USEIE | CCR_ULEIE | CCR_DTEIE; /* Enable Transfer state interrupts */