On Mon 11 Jan 09:16 CST 2021, Vinod Koul wrote:

bool?

+	struct dma_async_tx_descriptor *tx_desc;
+	struct dma_async_tx_descriptor *rx_desc;
+	enum i2c_se_mode se_mode;

bool gsi_only;

+	bool cmd_done;

Unused?

+	bool is_shared;

Used but meaningless?

Assign {} to config during declaration.

+	memset(&peripheral, 0, sizeof(peripheral));
+	config.peripheral_config = &peripheral;
+	config.peripheral_size = sizeof(peripheral);
+
+	if (!gi2c->tx_c) {
+		gi2c->tx_c = dma_request_slave_channel(gi2c->se.dev, "tx");

So object is reused for all future transfers as well?
Seems reasonable, but it should be released on driver removal?

Could it be requested at probe time instead?

+		if (!gi2c->tx_c) {
+			dev_err(gi2c->se.dev, "tx dma_request_slave_channel fail\n");
+			ret = -EIO;
+			goto geni_i2c_gsi_xfer_out;
+		}
+	}
+
+	if (!gi2c->rx_c) {
+		gi2c->rx_c = dma_request_slave_channel(gi2c->se.dev, "rx");
+		if (!gi2c->rx_c) {
+			dev_err(gi2c->se.dev, "rx dma_request_slave_channel fail\n");
+			ret = -EIO;
+			goto geni_i2c_gsi_xfer_out;
+		}
+	}
+
+	if (!gi2c->cfg_sent) {
+		const struct geni_i2c_clk_fld *itr = gi2c->clk_fld;
+
+		peripheral.pack_enable = I2C_PACK_EN;
+		peripheral.cycle_count = itr->t_cycle_cnt;
+		peripheral.high_count = itr->t_high_cnt;
+		peripheral.low_count = itr->t_low_cnt;
+		peripheral.clk_div = itr->clk_div;
+		gi2c->cfg_sent = true;

Is this a bool or an int?

+		peripheral.set_config =  true;

I find this somewhat ugly, you will always
dmaengine_slave_config(&config), but in the case of cfg_sent this will
point to an all-zero peripheral and hence will have set_config = false,
which will cause the skipping of setting up a configuration TRE.

I would prefer that the value of peripheral.set_config related to
cfg_sent in a more explicit fashion.

+	}
+
+	peripheral.multi_msg = false;
+	for (i = 0; i < num; i++) {
+		struct device *rx_dev = gi2c->se.wrapper->dev;
+		struct device *tx_dev = gi2c->se.wrapper->dev;
+		int stretch = (i < (num - 1));
+		u8 *dma_buf = NULL;

No need to initialize this, first use is an assignment.

+		unsigned int flags;
+
+		gi2c->cur = &msgs[i];
+
+		peripheral.addr = msgs[i].addr;
+		peripheral.stretch = stretch;
+		if (msgs[i].flags & I2C_M_RD)
+			peripheral.op = I2C_READ;
+		else
+			peripheral.op = I2C_WRITE;
+
+		dma_buf = i2c_get_dma_safe_msg_buf(&msgs[i], 1);
+		if (!dma_buf) {
+			ret = -ENOMEM;
+			goto geni_i2c_gsi_xfer_out;
+		}
+
+		if (msgs[i].flags & I2C_M_RD) {
+			gi2c->rx_ph = dma_map_single(rx_dev, dma_buf,
+						     msgs[i].len, DMA_FROM_DEVICE);
+			if (dma_mapping_error(rx_dev, gi2c->rx_ph)) {
+				dev_err(gi2c->se.dev, "dma_map_single for rx failed :%d\n", ret);
+				i2c_put_dma_safe_msg_buf(dma_buf, &msgs[i], false);
+				goto geni_i2c_gsi_xfer_out;
+			}
+
+			peripheral.op = I2C_READ;
+			peripheral.stretch = stretch;
+			ret = dmaengine_slave_config(gi2c->rx_c, &config);
+			if (ret) {
+				dev_err(gi2c->se.dev, "rx dma config error:%d\n", ret);
+				goto geni_i2c_gsi_xfer_out;

Need to unmap rx_ph?

+			}
+			peripheral.set_config =  false;
+			peripheral.multi_msg = true;
+			peripheral.rx_len = msgs[i].len;
+
+			flags = DMA_PREP_INTERRUPT | DMA_CTRL_ACK;
+			gi2c->rx_desc = dmaengine_prep_slave_single(gi2c->rx_c, gi2c->rx_ph,
+								    msgs[i].len,
+								    DMA_DEV_TO_MEM, flags);

Is the rx_desc freed by the dmaengine core when
dma_async_issue_pending() finishes it's job?

If so, why do you need to keep this pointer in gi2c? Wouldn't a local
variable suffice?

+			if (!gi2c->rx_desc) {
+				dev_err(gi2c->se.dev, "prep_slave_sg for rx failed\n");
+				gi2c->err = -EIO;
+				goto geni_i2c_err_prep_sg;
+			}
+
+			gi2c->rx_desc->callback_result = i2c_gsi_cb_result;
+			gi2c->rx_desc->callback_param = gi2c;
+
+			/* Issue RX */
+			gi2c->rx_cookie = dmaengine_submit(gi2c->rx_desc);
+			dma_async_issue_pending(gi2c->rx_c);
+		}
+
+		dev_dbg(gi2c->se.dev, "msg[%d].len:%d W\n", i, gi2c->cur->len);
+		gi2c->tx_ph = dma_map_single(tx_dev, dma_buf, msgs[i].len, DMA_TO_DEVICE);

Maybe I've forgotten something important about I2C, but why do we always
TX (even if it's a RX transfer)?

+		if (dma_mapping_error(tx_dev, gi2c->tx_ph)) {
+			dev_err(gi2c->se.dev, "dma_map_single for tx failed :%d\n", ret);
+			i2c_put_dma_safe_msg_buf(dma_buf, &msgs[i], false);

Need to unmap rx_ph?

+			goto geni_i2c_gsi_xfer_out;
+		}
+
+		peripheral.stretch = stretch;
+		peripheral.op = I2C_WRITE;
+		ret = dmaengine_slave_config(gi2c->tx_c, &config);
+		if (ret) {
+			dev_err(gi2c->se.dev, "tx dma config error:%d\n", ret);

Need to unmap rx_ph and tx_ph?

+			goto geni_i2c_gsi_xfer_out;
+		}
+		peripheral.set_config =  false;
+		peripheral.multi_msg = true;
+		gi2c->tx_desc = dmaengine_prep_slave_single(gi2c->tx_c, gi2c->tx_ph, msgs[i].len,
+							    DMA_MEM_TO_DEV,
+							    (DMA_PREP_INTERRUPT |  DMA_CTRL_ACK));
+		if (!gi2c->tx_desc) {
+			dev_err(gi2c->se.dev, "prep_slave_sg for tx failed\n");
+			gi2c->err = -ENOMEM;
+			goto geni_i2c_err_prep_sg;
+		}
+		gi2c->tx_desc->callback_result = i2c_gsi_cb_result;
+		gi2c->tx_desc->callback_param = gi2c;
+
+		/* Issue TX */
+		gi2c->tx_cookie = dmaengine_submit(gi2c->tx_desc);
+		dma_async_issue_pending(gi2c->tx_c);
+
+		timeout = wait_for_completion_timeout(&gi2c->done, XFER_TIMEOUT);
+		if (!timeout) {
+			dev_err(gi2c->se.dev, "I2C timeout gsi flags:%d addr:0x%x\n",
+				gi2c->cur->flags, gi2c->cur->addr);
+			gi2c->err = -ETIMEDOUT;
+		}
+geni_i2c_err_prep_sg:

Perhaps you can break the body of this loop out to a separate function
and thereby avoid the goto within the block?

+		if (gi2c->err) {
+			dmaengine_terminate_all(gi2c->tx_c);
+			gi2c->cfg_sent = 0;

Is this a bool or an int?

+		}
+		if (msgs[i].flags & I2C_M_RD)
+			dma_unmap_single(rx_dev, gi2c->rx_ph, msgs[i].len, DMA_FROM_DEVICE);

You unconditionally map tx_ph, but you only unmap it on ~I2C_M_RD. This
fits better with my expectation, but would mean that the whole tx block
above should be in an else.

+		else
+			dma_unmap_single(tx_dev, gi2c->tx_ph, msgs[i].len, DMA_TO_DEVICE);
+		i2c_put_dma_safe_msg_buf(dma_buf, &msgs[i], !gi2c->err);
+		if (gi2c->err)
+			goto geni_i2c_gsi_xfer_out;

This goto is just a "break" in disguise.

Rather than goto skip_non_gsi_code; I think you should move the non-gsi
part of this function into a separate fifo function and make this

if (GSI_ONLY)
	ret = geni_i2c_gsi_xfer();
else
	ret = geni_i2c_fifo_xfer();

+	} else {
+		/* Don't set shared flag in non-GSI mode */
+		gi2c->is_shared = false;

I don't see this flag being looked at elsewhere.

Please declare your variables at the top of the function.

+
+		if (unlikely(proto != GENI_SE_I2C)) {

If this was the case at probe time the driver would never have probed,
why has it changed?

This is not a fastpath, so skip the unlikely()

+			dev_err(gi2c->se.dev, "Invalid proto %d\n", proto);
+			geni_se_resources_off(&gi2c->se);
+			return -ENXIO;
+		}
+
+		se_mode = readl_relaxed(gi2c->se.base + GENI_IF_DISABLE_RO) &
+				FIFO_IF_DISABLE;

se_mode would better be called "fifo_disabled" or perhaps logically
suited "gsi_only"?

Please skip the _relaxed

+		if (se_mode) {
+			gi2c->se_mode = GSI_ONLY;
+			geni_se_select_mode(&gi2c->se, GENI_GPI_DMA);
+			dev_dbg(gi2c->se.dev, "i2c GSI mode\n");
+		} else {
+			int gi2c_tx_depth = geni_se_get_tx_fifo_depth(&gi2c->se);

This variable has an unnecessarily long name.

+
+			gi2c->se_mode = FIFO_SE_DMA;
+			gi2c->tx_wm = gi2c_tx_depth - 1;
+			geni_se_init(&gi2c->se, gi2c->tx_wm, gi2c_tx_depth);
+			geni_se_config_packing(&gi2c->se, BITS_PER_BYTE,
+					       PACKING_BYTES_PW, true, true, true);
+			qcom_geni_i2c_conf(gi2c);
+			dev_dbg(gi2c->se.dev,
+				"i2c fifo/se-dma mode. fifo depth:%d\n", gi2c_tx_depth);
+		}
+		dev_dbg(gi2c->se.dev, "i2c-%d: %s\n",
+			gi2c->adap.nr, dev_name(gi2c->se.dev));

dev_dbg() already provides dev_name. What information does this debug
print actually try to communicate?

Regards,
Bjorn

+	}
+
+	if (gi2c->se_mode == FIFO_SE_DMA)
+		enable_irq(gi2c->irq);
 
-	enable_irq(gi2c->irq);
 	gi2c->suspended = 0;
 	return 0;
 }
-- 
2.26.2