| Message ID | 20241015120750.21217-1-quic_jseerapu@quicinc.com |
|---|---|
| Headers | show |
| Series | Add Block event interrupt support for I2C protocol | expand |
On Tue, 15 Oct 2024 17:37:46 +0530, Jyothi Kumar Seerapu wrote: > When high performance with multiple i2c messages in a single transfer > is required, employ Block Event Interrupt (BEI) to trigger interrupts > after specific messages transfer and the last message transfer, > thereby reducing interrupts. > > For each i2c message transfer, a series of Transfer Request Elements(TREs) > must be programmed, including config tre for frequency configuration, > go tre for holding i2c address and dma tre for holding dma buffer address, > length as per the hardware programming guide. For transfer using BEI, > multiple I2C messages may necessitate the preparation of config, go, > and tx DMA TREs. However, a channel TRE size of 64 is often insufficient, > potentially leading to failures due to inadequate memory space. > > Add additional argument to dma-cell property for channel TRE size. > With this, adjust the channel TRE size via the device tree. > The default size is 64, but clients can modify this value based on > their specific requirements. > > Signed-off-by: Jyothi Kumar Seerapu <quic_jseerapu@quicinc.com> > --- > Documentation/devicetree/bindings/dma/qcom,gpi.yaml | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > My bot found errors running 'make dt_binding_check' on your patch: yamllint warnings/errors: dtschema/dtc warnings/errors: /builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/dma/qcom,gpi.yaml: properties:#dma-cells: 'minItems' is not one of ['description', 'deprecated', 'const', 'enum', 'minimum', 'maximum', 'multipleOf', 'default', '$ref', 'oneOf'] from schema $id: http://devicetree.org/meta-schemas/core.yaml# /builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/dma/qcom,gpi.yaml: properties:#dma-cells: 'maxItems' is not one of ['description', 'deprecated', 'const', 'enum', 'minimum', 'maximum', 'multipleOf', 'default', '$ref', 'oneOf'] from schema $id: http://devicetree.org/meta-schemas/core.yaml# doc reference errors (make refcheckdocs): See https://patchwork.ozlabs.org/project/devicetree-bindings/patch/20241015120750.21217-2-quic_jseerapu@quicinc.com The base for the series is generally the latest rc1. A different dependency should be noted in *this* patch. If you already ran 'make dt_binding_check' and didn't see the above error(s), then make sure 'yamllint' is installed and dt-schema is up to date: pip3 install dtschema --upgrade Please check and re-submit after running the above command yourself. Note that DT_SCHEMA_FILES can be set to your schema file to speed up checking your schema. However, it must be unset to test all examples with your schema.
On Tue, Oct 15, 2024 at 05:37:46PM +0530, Jyothi Kumar Seerapu wrote: > When high performance with multiple i2c messages in a single transfer > is required, employ Block Event Interrupt (BEI) to trigger interrupts > after specific messages transfer and the last message transfer, > thereby reducing interrupts. > > For each i2c message transfer, a series of Transfer Request Elements(TREs) > must be programmed, including config tre for frequency configuration, > go tre for holding i2c address and dma tre for holding dma buffer address, > length as per the hardware programming guide. For transfer using BEI, > multiple I2C messages may necessitate the preparation of config, go, > and tx DMA TREs. However, a channel TRE size of 64 is often insufficient, > potentially leading to failures due to inadequate memory space. > > Add additional argument to dma-cell property for channel TRE size. No such property 'dma-cell' > With this, adjust the channel TRE size via the device tree. > The default size is 64, but clients can modify this value based on > their specific requirements. > > Signed-off-by: Jyothi Kumar Seerapu <quic_jseerapu@quicinc.com> > --- > Documentation/devicetree/bindings/dma/qcom,gpi.yaml | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/Documentation/devicetree/bindings/dma/qcom,gpi.yaml b/Documentation/devicetree/bindings/dma/qcom,gpi.yaml > index 4df4e61895d2..002495921643 100644 > --- a/Documentation/devicetree/bindings/dma/qcom,gpi.yaml > +++ b/Documentation/devicetree/bindings/dma/qcom,gpi.yaml > @@ -54,14 +54,16 @@ properties: > maxItems: 13 > > "#dma-cells": > - const: 3 > + minItems: 3 > + maxItems: 4 > description: > > DMA clients must use the format described in dma.txt, giving a phandle > - to the DMA controller plus the following 3 integer cells: > + to the DMA controller plus the following 4 integer cells: > - channel: if set to 0xffffffff, any available channel will be allocated > for the client. Otherwise, the exact channel specified will be used. > - seid: serial id of the client as defined in the SoC documentation. > - client: type of the client as defined in dt-bindings/dma/qcom-gpi.h > + - channel-tre-size: size of the channel TRE (transfer ring element) > > iommus: > maxItems: 1 > -- > 2.17.1 >
Hi Jyothi, ... > @@ -523,26 +576,49 @@ static int geni_i2c_gpi(struct geni_i2c_dev *gi2c, struct i2c_msg *msg, > enum dma_transfer_direction dma_dirn; > struct dma_async_tx_descriptor *desc; > int ret; > + struct gpi_multi_xfer *gi2c_gpi_xfer; > + dma_cookie_t cookie; > > peripheral = config->peripheral_config; > - > - dma_buf = i2c_get_dma_safe_msg_buf(msg, 1); > - if (!dma_buf) > + gi2c_gpi_xfer = &peripheral->multi_xfer; > + gi2c_gpi_xfer->msg_idx_cnt = cur_msg_idx; > + dma_buf = gi2c_gpi_xfer->dma_buf[gi2c_gpi_xfer->buf_idx]; > + addr = gi2c_gpi_xfer->dma_addr[gi2c_gpi_xfer->buf_idx]; > + > + dma_buf = i2c_get_dma_safe_msg_buf(&msgs[gi2c_gpi_xfer->msg_idx_cnt], 1); > + if (!dma_buf) { > + gi2c->err = -ENOMEM; > return -ENOMEM; > + } > > if (op == I2C_WRITE) > map_dirn = DMA_TO_DEVICE; > else > map_dirn = DMA_FROM_DEVICE; > > - addr = dma_map_single(gi2c->se.dev->parent, dma_buf, msg->len, map_dirn); > + addr = dma_map_single(gi2c->se.dev->parent, > + dma_buf, msgs[gi2c_gpi_xfer->msg_idx_cnt].len, You could save msgs[gi2c_gpi_xfer->msg_idx_cnt] in a separate variable to avoid this extra indexing. > + map_dirn); > if (dma_mapping_error(gi2c->se.dev->parent, addr)) { > - i2c_put_dma_safe_msg_buf(dma_buf, msg, false); > + i2c_put_dma_safe_msg_buf(dma_buf, &msgs[gi2c_gpi_xfer->msg_idx_cnt], > + false); > + gi2c->err = -ENOMEM; > return -ENOMEM; > } > > + if (gi2c->is_tx_multi_xfer) { > + if (((gi2c_gpi_xfer->msg_idx_cnt + 1) % NUM_MSGS_PER_IRQ)) > + peripheral->flags |= QCOM_GPI_BLOCK_EVENT_IRQ; > + else > + peripheral->flags &= ~QCOM_GPI_BLOCK_EVENT_IRQ; > + > + /* BEI bit to be cleared for last TRE */ > + if (gi2c_gpi_xfer->msg_idx_cnt == gi2c->num_msgs - 1) > + peripheral->flags &= ~QCOM_GPI_BLOCK_EVENT_IRQ; > + } > + > /* set the length as message for rx txn */ > - peripheral->rx_len = msg->len; > + peripheral->rx_len = msgs[gi2c_gpi_xfer->msg_idx_cnt].len; > peripheral->op = op; > > ret = dmaengine_slave_config(dma_chan, config); > @@ -560,25 +636,56 @@ static int geni_i2c_gpi(struct geni_i2c_dev *gi2c, struct i2c_msg *msg, > else > dma_dirn = DMA_DEV_TO_MEM; > > - desc = dmaengine_prep_slave_single(dma_chan, addr, msg->len, dma_dirn, flags); > + desc = dmaengine_prep_slave_single(dma_chan, addr, > + msgs[gi2c_gpi_xfer->msg_idx_cnt].len, > + dma_dirn, flags); > if (!desc) { > dev_err(gi2c->se.dev, "prep_slave_sg failed\n"); > - ret = -EIO; > + gi2c->err = -EIO; > goto err_config; > } > > desc->callback_result = i2c_gpi_cb_result; > desc->callback_param = gi2c; > > - dmaengine_submit(desc); > - *buf = dma_buf; > - *dma_addr_p = addr; > + if (!((msgs[cur_msg_idx].flags & I2C_M_RD) && op == I2C_WRITE)) { > + gi2c_gpi_xfer->msg_idx_cnt++; > + gi2c_gpi_xfer->buf_idx = (cur_msg_idx + 1) % QCOM_GPI_MAX_NUM_MSGS; > + } > + cookie = dmaengine_submit(desc); > + if (dma_submit_error(cookie)) { > + dev_err(gi2c->se.dev, > + "%s: dmaengine_submit failed (%d)\n", __func__, cookie); > + return -EINVAL; goto err_config? > + } > > + if (gi2c->is_tx_multi_xfer) { > + dma_async_issue_pending(gi2c->tx_c); > + if ((cur_msg_idx == (gi2c->num_msgs - 1)) || > + (gi2c_gpi_xfer->msg_idx_cnt >= > + QCOM_GPI_MAX_NUM_MSGS + gi2c_gpi_xfer->freed_msg_cnt)) { > + ret = gpi_multi_desc_process(gi2c->se.dev, gi2c_gpi_xfer, > + gi2c->num_msgs, XFER_TIMEOUT, > + &gi2c->done); > + if (ret) { > + dev_dbg(gi2c->se.dev, > + "I2C multi write msg transfer timeout: %d\n", > + ret); if you are returning an error, then print an error. > + gi2c->err = -ETIMEDOUT; gi2c->err = ret? > + goto err_config; > + } > + } > + } else { > + /* Non multi descriptor message transfer */ > + *buf = dma_buf; > + *dma_addr_p = addr; > + } > return 0; > > err_config: > - dma_unmap_single(gi2c->se.dev->parent, addr, msg->len, map_dirn); > - i2c_put_dma_safe_msg_buf(dma_buf, msg, false); > + dma_unmap_single(gi2c->se.dev->parent, addr, > + msgs[cur_msg_idx].len, map_dirn); > + i2c_put_dma_safe_msg_buf(dma_buf, &msgs[cur_msg_idx], false); > return ret; I would have one more label here: out: gi2c->err = ret; return ret; in order to avoid always assigning twice > } > > @@ -590,6 +697,7 @@ static int geni_i2c_gpi_xfer(struct geni_i2c_dev *gi2c, struct i2c_msg msgs[], i > unsigned long time_left; > dma_addr_t tx_addr, rx_addr; > void *tx_buf = NULL, *rx_buf = NULL; > + struct gpi_multi_xfer *tx_multi_xfer; > const struct geni_i2c_clk_fld *itr = gi2c->clk_fld; > > config.peripheral_config = &peripheral; > @@ -603,6 +711,39 @@ static int geni_i2c_gpi_xfer(struct geni_i2c_dev *gi2c, struct i2c_msg msgs[], i > peripheral.set_config = 1; > peripheral.multi_msg = false; > > + gi2c->gpi_config = &peripheral; > + gi2c->num_msgs = num; > + gi2c->is_tx_multi_xfer = false; > + gi2c->tx_irq_cnt = 0; > + > + tx_multi_xfer = &peripheral.multi_xfer; > + tx_multi_xfer->msg_idx_cnt = 0; > + tx_multi_xfer->buf_idx = 0; > + tx_multi_xfer->unmap_msg_cnt = 0; > + tx_multi_xfer->freed_msg_cnt = 0; > + tx_multi_xfer->irq_msg_cnt = 0; > + tx_multi_xfer->irq_cnt = 0; you can initialize tx_multi_xfer to "{ };" to avoid all these " = 0" > + > + /* > + * If number of write messages are four and higher then > + * configure hardware for multi descriptor transfers with BEI. > + */ > + if (num >= MIN_NUM_OF_MSGS_MULTI_DESC) { > + gi2c->is_tx_multi_xfer = true; > + for (i = 0; i < num; i++) { > + if (msgs[i].flags & I2C_M_RD) { > + /* > + * Multi descriptor transfer with BEI > + * support is enabled for write transfers. > + * Add BEI optimization support for read > + * transfers later. > + */ > + gi2c->is_tx_multi_xfer = false; > + break; > + } > + } > + } > + > for (i = 0; i < num; i++) { > gi2c->cur = &msgs[i]; > gi2c->err = 0; > @@ -613,14 +754,16 @@ static int geni_i2c_gpi_xfer(struct geni_i2c_dev *gi2c, struct i2c_msg msgs[], i > peripheral.stretch = 1; > > peripheral.addr = msgs[i].addr; > + if (i > 0 && (!(msgs[i].flags & I2C_M_RD))) > + peripheral.multi_msg = false; > > - ret = geni_i2c_gpi(gi2c, &msgs[i], &config, > + ret = geni_i2c_gpi(gi2c, msgs, i, &config, what is the point of passing 'i' if you always refer to msgs[i] in geni_i2c_gpi()? > &tx_addr, &tx_buf, I2C_WRITE, gi2c->tx_c); > if (ret) > goto err; > > if (msgs[i].flags & I2C_M_RD) { > - ret = geni_i2c_gpi(gi2c, &msgs[i], &config, > + ret = geni_i2c_gpi(gi2c, msgs, i, &config, > &rx_addr, &rx_buf, I2C_READ, gi2c->rx_c); > if (ret) > goto err; > @@ -628,18 +771,28 @@ static int geni_i2c_gpi_xfer(struct geni_i2c_dev *gi2c, struct i2c_msg msgs[], i > dma_async_issue_pending(gi2c->rx_c); > } > > - dma_async_issue_pending(gi2c->tx_c); > - > - time_left = wait_for_completion_timeout(&gi2c->done, XFER_TIMEOUT); > - if (!time_left) > - gi2c->err = -ETIMEDOUT; > + if (!gi2c->is_tx_multi_xfer) { > + dma_async_issue_pending(gi2c->tx_c); > + time_left = wait_for_completion_timeout(&gi2c->done, XFER_TIMEOUT); > + if (!time_left) { > + dev_err(gi2c->se.dev, "%s:I2C timeout\n", __func__); > + gi2c->err = -ETIMEDOUT; > + } > + } > > if (gi2c->err) { > ret = gi2c->err; > goto err; > } > > - geni_i2c_gpi_unmap(gi2c, &msgs[i], tx_buf, tx_addr, rx_buf, rx_addr); > + if (!gi2c->is_tx_multi_xfer) { > + geni_i2c_gpi_unmap(gi2c, &msgs[i], tx_buf, tx_addr, rx_buf, rx_addr); > + } else { > + if (gi2c->tx_irq_cnt != tx_multi_xfer->irq_cnt) { else if (...) { ... } Andi
The I2C driver gets an interrupt upon transfer completion. For multiple messages in a single transfer, N interrupts will be received for N messages, leading to significant software interrupt latency. To mitigate this latency, utilize Block Event Interrupt (BEI) only when an interrupt is necessary. This means large transfers can be split into multiple chunks of 64 messages internally, without expecting interrupts for the first 63 transfers, only the last one will trigger an interrupt indicating 64 transfers completed. By implementing BEI, multi-message transfers can be divided into chunks of 64 messages, improving overall transfer time. 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. Jyothi Kumar Seerapu (5): dt-bindings: dmaengine: qcom: gpi: Add additional arg to dma-cell property arm64: dts: qcom: Add support for configuring channel TRE size dmaengine: qcom: gpi: Add provision to support TRE size as the fourth argument of dma-cells property dmaengine: qcom: gpi: Add GPI Block event interrupt support i2c: i2c-qcom-geni: Add Block event interrupt support .../devicetree/bindings/dma/qcom,gpi.yaml | 6 +- arch/arm64/boot/dts/qcom/sc7280.dtsi | 132 +++++------ drivers/dma/qcom/gpi.c | 74 ++++++- drivers/i2c/busses/i2c-qcom-geni.c | 205 ++++++++++++++++-- include/linux/dma/qcom-gpi-dma.h | 37 ++++ 5 files changed, 355 insertions(+), 99 deletions(-) base-commit: 55bcd2e0d04c1171d382badef1def1fd04ef66c5