Hi, this patch has been hanging here for a while, can we please have someone from DMA and Qualcomm look at it? Thanks, Andi On Tue, Dec 17, 2024 at 10:34:22PM +0530, Jyothi Kumar Seerapu wrote: > The I2C driver gets an interrupt upon transfer completion. > When handling multiple messages in a single transfer, this > results in N interrupts for N messages, leading to significant > software interrupt latency. > > To mitigate this latency, utilize Block Event Interrupt (BEI) > mechanism. Enabling BEI instructs the hardware to prevent interrupt > generation and BEI is disabled when an interrupt is necessary. > > Large I2C transfer can be divided into chunks of 8 messages internally. > Interrupts are not expected for the first 7 message completions, only > the last message triggers an interrupt, indicating the completion of > 8 messages. This BEI mechanism enhances overall transfer efficiency. > > This optimization reduces transfer time from 168 ms to 48 ms for a > series of 200 I2C write messages in a single transfer, with a > clock frequency support of 100 kHz. > > BEI optimizations are currently implemented for I2C write transfers only, > as there is no use case for multiple I2C read messages in a single transfer > at this time. > > v3 -> v4: > - API's added for Block event interrupt with multi descriptor support is > moved from qcom-gpi-dma.h file to I2C geni qcom driver file. > - gpi_multi_xfer_timeout_handler function is moved from GPI driver to > I2C driver. > - geni_i2c_gpi_multi_desc_xfer structure is added as a member of > struct geni_i2c_dev. > - Removed the changes of making I2C driver is dependent on GPI driver. > > v2 -> v3: > - Updated commit description > - In I2C GENI driver, for i2c_gpi_cb_result moved the logic of > "!is_tx_multi_xfer" to else part. > - MIN_NUM_OF_MSGS_MULTI_DESC changed from 4 to 2 > - Changes of I2C GENI driver to depend on the GPI driver moved > to patch3. > - Renamed gpi_multi_desc_process to gpi_multi_xfer_timeout_handler > - Added description for newly added changes in "qcom-gpi-dma.h" file. > > v1 -> v2: > - DT changes are reverted for adding dma channel size as a new arg of > dma-cells property. > - DT binding change reveted for dma channel size as a new arg of > dma-cells property. > - In GPI driver, reverted the changes to parse the channel TRE size > from device tree. > - Made the changes in QCOM I2C geni driver to support the BEI > functionality with the existing TRE size of 64. > - Made changes in QCOM I2C geni driver as per the review comments. > - Fixed Kernel test robot reported compiltion issues. > > > Jyothi Kumar Seerapu (2): > dmaengine: qcom: gpi: Add GPI Block event interrupt support > i2c: i2c-qcom-geni: Add Block event interrupt support > > drivers/dma/qcom/gpi.c | 3 + > drivers/i2c/busses/i2c-qcom-geni.c | 275 ++++++++++++++++++++++++++--- > include/linux/dma/qcom-gpi-dma.h | 9 + > 3 files changed, 262 insertions(+), 25 deletions(-) > > -- > 2.17.1 >
