kernel/linux.git/drivers/dma/dw, branch linux-5.11.y

dmaengine: dw: Make it dependent to HAS_IOMEM

2021-04-21T11:13:18+00:00

[ Upstream commit 88cd1d6191b13689094310c2405394e4ce36d061 ] Some architectures do not provide devm_*() APIs. Hence make the driver dependent on HAVE_IOMEM. Fixes: dbde5c2934d1 ("dw_dmac: use devm_* functions to simplify code") Reported-by: kernel test robot Signed-off-by: Andy Shevchenko Acked-by: Viresh Kumar Link: https://lore.kernel.org/r/20210324141757.24710-1-andriy.shevchenko@linux.intel.com Signed-off-by: Vinod Koul Signed-off-by: Sasha Levin

dmaengine dw: Revert "dmaengine: dw: Enable runtime PM"

2021-02-08T12:06:12+00:00

This reverts commit 842067940a3e3fc008a60fee388e000219b32632. For some solutions e.g. sound/soc/intel/catpt, DW DMA is part of a compound device (in that very example, domains: ADSP, SSP0, SSP1, DMA0 and DMA1 are part of a single entity) rather than being a standalone one. Driver for said device may enlist DMA to transfer data during suspend or resume sequences. Manipulating RPM explicitly in dw's DMA request and release channel functions causes suspend() to also invoke resume() for the exact same device. Similar situation occurs for resume() sequence. Effectively renders device dysfunctional after first suspend() attempt. Revert the change to address the problem. Fixes: 842067940a3e ("dmaengine: dw: Enable runtime PM") Cc: Andy Shevchenko Signed-off-by: Cezary Rojewski Acked-by: Andy Shevchenko Link: https://lore.kernel.org/r/20210203191924.15706-1-cezary.rojewski@intel.com Signed-off-by: Vinod Koul

dmaengine: dw: Enable runtime PM

2020-11-09T11:49:20+00:00

When consumer requests channel power on the DMA controller device and otherwise on the freeing channel resources. Note, in some cases consumer acquires channel at the ->probe() stage and releases it at the ->remove() stage. It will mean that DMA controller device will be powered during all this time if there is no assist from hardware to idle it. The above mentioned cases should be investigated separately and individually. Signed-off-by: Andy Shevchenko Acked-by: Viresh Kumar Link: https://lore.kernel.org/r/20201103183938.64752-1-andriy.shevchenko@linux.intel.com Signed-off-by: Vinod Koul

dmaengine: dw: convert tasklets to use new tasklet_setup() API

2020-09-18T06:48:11+00:00

In preparation for unconditionally passing the struct tasklet_struct pointer to all tasklet callbacks, switch to using the new tasklet_setup() and from_tasklet() to pass the tasklet pointer explicitly. Signed-off-by: Romain Perier Signed-off-by: Allen Pais Link: https://lore.kernel.org/r/20200831103542.305571-6-allen.lkml@gmail.com Signed-off-by: Vinod Koul

dmaengine: dw: Add DMA-channels mask cell support

2020-08-17T06:28:31+00:00

DW DMA IP-core provides a way to synthesize the DMA controller with channels having different parameters like maximum burst-length, multi-block support, maximum data width, etc. Those parameters both explicitly and implicitly affect the channels performance. Since DMA slave devices might be very demanding to the DMA performance, let's provide a functionality for the slaves to be assigned with DW DMA channels, which performance according to the platform engineer fulfill their requirements. After this patch is applied it can be done by passing the mask of suitable DMA-channels either directly in the dw_dma_slave structure instance or as a fifth cell of the DMA DT-property. If mask is zero or not provided, then there is no limitation on the channels allocation. For instance Baikal-T1 SoC is equipped with a DW DMAC engine, which first two channels are synthesized with max burst length of 16, while the rest of the channels have been created with max-burst-len=4. It would seem that the first two channels must be faster than the others and should be more preferable for the time-critical DMA slave devices. In practice it turned out that the situation is quite the opposite. The channels with max-burst-len=4 demonstrated a better performance than the channels with max-burst-len=16 even when they both had been initialized with the same settings. The performance drop of the first two DMA-channels made them unsuitable for the DW APB SSI slave device. No matter what settings they are configured with, full-duplex SPI transfers occasionally experience the Rx FIFO overflow. It means that the DMA-engine doesn't keep up with incoming data pace even though the SPI-bus is enabled with speed of 25MHz while the DW DMA controller is clocked with 50MHz signal. There is no such problem has been noticed for the channels synthesized with max-burst-len=4. Signed-off-by: Serge Semin Link: https://lore.kernel.org/r/20200731200826.9292-6-Sergey.Semin@baikalelectronics.ru Signed-off-by: Vinod Koul

dmaengine: dw: Ignore burst setting for memory peripherals

2020-08-17T06:28:31+00:00

According to the DW DMA controller Databook 2.18b (page 40 "3.5 Memory Peripherals") memory peripherals don't have handshaking interface connected to the controller, therefore they can never be a flow controller. Since the CTLx.SRC_MSIZE and CTLx.DEST_MSIZE are properties valid only for peripherals with a handshaking interface, we can freely zero these fields out if the memory peripheral is selected to be the source or the destination of the DMA transfers. Note according to the databook, length of burst transfers to memory is always equal to the number of data items available in a channel FIFO or data items required to complete the block transfer, whichever is smaller; length of burst transfers from memory is always equal to the space available in a channel FIFO or number of data items required to complete the block transfer, whichever is smaller. Signed-off-by: Serge Semin Link: https://lore.kernel.org/r/20200731200826.9292-5-Sergey.Semin@baikalelectronics.ru Signed-off-by: Vinod Koul

dmaengine: dw: Discard dlen from the dev-to-mem xfer width calculation

2020-08-17T06:28:31+00:00

Indeed in case of the DMA_DEV_TO_MEM DMA transfers it's enough to take the destination memory address and the destination master data width into account to calculate the CTLx.DST_TR_WIDTH setting of the memory peripheral. According to the DW DMAC IP-core Databook 2.18b (page 66, Example 5) at the and of a DMA transfer when the DMA-channel internal FIFO is left with data less than for a single destination burst transaction, the destination peripheral will enter the Single Transaction Region where the DW DMA controller can complete a block transfer to the destination using single transactions (non-burst transaction of CTLx.DST_TR_WIDTH bytes). If there is no enough data in the DMA-channel internal FIFO for even a single non-burst transaction of CTLx.DST_TR_WIDTH bytes, then the channel enters "FIFO flush mode". That mode is activated to empty the FIFO and flush the leftovers out to the memory peripheral. The flushing procedure is simple. The data is sent to the memory by means of a set of single transaction of CTLx.SRC_TR_WIDTH bytes. To sum up it's redundant to use the LLPs length to find out the CTLx.DST_TR_WIDTH parameter value, since each DMA transfer will be completed with the CTLx.SRC_TR_WIDTH bytes transaction if it is required. We suggest to remove the LLP entry length from the statement which calculates the memory peripheral DMA transaction width since it's redundant due to the feature described above. By doing so we'll improve the memory bus utilization and speed up the DMA-channel performance for DMA_DEV_TO_MEM DMA-transfers. Signed-off-by: Serge Semin Acked-by: Andy Shevchenko Link: https://lore.kernel.org/r/20200731200826.9292-4-Sergey.Semin@baikalelectronics.ru Signed-off-by: Vinod Koul

dmaengine: dw: Activate FIFO-mode for memory peripherals only

2020-08-17T06:28:31+00:00

CFGx.FIFO_MODE field controls a DMA-controller "FIFO readiness" criterion. In other words it determines when to start pushing data out of a DW DMAC channel FIFO to a destination peripheral or from a source peripheral to the DW DMAC channel FIFO. Currently FIFO-mode is set to one for all DW DMAC channels. It means they are tuned to flush data out of FIFO (to a memory peripheral or by accepting the burst transaction requests) when FIFO is at least half-full (except at the end of the block transfer, when FIFO-flush mode is activated) and are configured to get data to the FIFO when it's at least half-empty. Such configuration is a good choice when there is no slave device involved in the DMA transfers. In that case the number of bursts per block is less than when CFGx.FIFO_MODE = 0 and, hence, the bus utilization will improve. But the latency of DMA transfers may increase when CFGx.FIFO_MODE = 1, since DW DMAC will wait for the channel FIFO contents to be either half-full or half-empty depending on having the destination or the source transfers. Such latencies might be dangerous in case if the DMA transfers are expected to be performed from/to a slave device. Since normally peripheral devices keep data in internal FIFOs, any latency at some critical moment may cause one being overflown and consequently losing data. This especially concerns a case when either a peripheral device is relatively fast or the DW DMAC engine is relatively slow with respect to the incoming data pace. In order to solve problems, which might be caused by the latencies described above, let's enable the FIFO half-full/half-empty "FIFO readiness" criterion only for DMA transfers with no slave device involved. Thanks to the commit 99ba8b9b0d97 ("dmaengine: dw: Initialize channel before each transfer") we can freely do that in the generic dw_dma_initialize_chan() method. Signed-off-by: Serge Semin Reviewed-by: Andy Shevchenko Link: https://lore.kernel.org/r/20200731200826.9292-3-Sergey.Semin@baikalelectronics.ru Signed-off-by: Vinod Koul

Merge branch 'for-linus' into fixes

2020-08-05T13:32:07+00:00

Signed-off-by: Vinod Koul Conflicts: drivers/dma/idxd/sysfs.c

dmaengine: dw: Initialize max_sg_burst capability

2020-07-27T09:00:55+00:00

Multi-block support provides a way to map the kernel-specific SG-table so the DW DMA device would handle it as a whole instead of handling the SG-list items or so called LLP block items one by one. So if true LLP list isn't supported by the DW DMA engine, then soft-LLP mode will be utilized to load and execute each LLP-block one by one. The soft-LLP mode of the DMA transactions execution might not work well for some DMA consumers like SPI due to its Tx and Rx buffers inter-dependency. Let's initialize the max_sg_burst DMA channels capability based on the nollp flag state. If it's true, no hardware accelerated LLP is available and max_sg_burst should be set with 1, which means that the DMA engine can handle only a single SG list entry at a time. If noLLP is set to false, then hardware accelerated LLP is supported and the DMA engine can handle infinite number of SG entries in a single DMA transaction. Signed-off-by: Serge Semin Reviewed-by: Andy Shevchenko Link: https://lore.kernel.org/r/20200723005848.31907-11-Sergey.Semin@baikalelectronics.ru Signed-off-by: Vinod Koul