Re: [PATCH v2] mmc: mmci: Add qcom dml support to the driver.

From: Srinivas Kandagatla
Date: Fri Jul 25 2014 - 00:07:44 EST



On 23/07/14 23:58, Stephen Boyd wrote:
On 07/18/14 13:53, Srinivas Kandagatla wrote:

@@ -468,6 +473,11 @@ static void mmci_dma_setup(struct mmci_host *host)
if (max_seg_size < host->mmc->max_seg_size)
host->mmc->max_seg_size = max_seg_size;
}
+
+ if (variant->qcom_dml && host->dma_rx_channel && host->dma_tx_channel) {
+ if (dml_hw_init(host, host->mmc->parent->of_node))
+ variant->qcom_dml = false;
+ }

Style nit: Braces aren't needed.
Will fix it in next spin.

+
+void dml_start_xfer(struct mmci_host *host, struct mmc_data *data)
+{
+ u32 config;
+ void __iomem *base = host->base + DML_OFFSET;
+
+ if (data->flags & MMC_DATA_READ) {
+ /* Read operation: configure DML for producer operation */
+ /* Set producer CRCI-x and disable consumer CRCI */
+ config = readl_relaxed(base + DML_CONFIG);
+ config = (config & ~PRODUCER_CRCI_MSK) | PRODUCER_CRCI_X_SEL;
+ config = (config & ~CONSUMER_CRCI_MSK) | CONSUMER_CRCI_DISABLE;
+ writel_relaxed(config, base + DML_CONFIG);
+
+ /* Set the Producer BAM block size */
+ writel_relaxed(data->blksz, base + DML_PRODUCER_BAM_BLOCK_SIZE);
+
+ /* Set Producer BAM Transaction size */
+ writel_relaxed(data->blocks * data->blksz,
+ base + DML_PRODUCER_BAM_TRANS_SIZE);
+ /* Set Producer Transaction End bit */
+ config = readl_relaxed(base + DML_CONFIG);
+ config |= PRODUCER_TRANS_END_EN;
+ writel_relaxed(config, base + DML_CONFIG);
+ /* Trigger producer */
+ writel_relaxed(1, base + DML_PRODUCER_START);
+ } else {
+ /* Write operation: configure DML for consumer operation */
+ /* Set consumer CRCI-x and disable producer CRCI*/
+ config = readl_relaxed(base + DML_CONFIG);
+ config = (config & ~CONSUMER_CRCI_MSK) | CONSUMER_CRCI_X_SEL;
+ config = (config & ~PRODUCER_CRCI_MSK) | PRODUCER_CRCI_DISABLE;
+ writel_relaxed(config, base + DML_CONFIG);
+ /* Clear Producer Transaction End bit */
+ config = readl_relaxed(base + DML_CONFIG);
+ config &= ~PRODUCER_TRANS_END_EN;
+ writel_relaxed(config, base + DML_CONFIG);
+ /* Trigger consumer */
+ writel_relaxed(1, base + DML_CONSUMER_START);
+ }

I think we need a memory barrier here. Does the DML need to be enabled
before the mmci driver sets MCI_DPSM_DMAENABLE? My understanding is that
relaxed accesses to different devices aren't ordered with respect to one
another. So not having a memory barrier here could cause the
consumer/producer to be enabled after MCI_DPSM_DMAENABLE is set in the
mmci hardware. Downstream I see that we have an mb(), but I think we
could just a wmb() because we're just ordering with the mmci hardware right?
yes, I think wmb should work. I will fix this.


Is there any ordering required between bam and dml? I think enabling bam
could happen after enabling the consumer unless we had a wmb() after we
kick off bam and before we write a 1 to DML_CONSUMER_START.

Am not sure if there is any strict ordering requirement between bam and dml. But I can see a wmb in bam_start_dma().

+}
+
+static int of_get_dml_pipe_index(struct device_node *np, const char *name)

return type of u32?

This function is expected to return negative error codes. I think I should change u32 to int in dml_hw_init().

+{
+ int index;
+ struct of_phandle_args dma_spec;
+
+ index = of_property_match_string(np, "dma-names", name);
+
+ if (index < 0)
+ return -ENODEV;
+
+ if (of_parse_phandle_with_args(np, "dmas", "#dma-cells", index,
+ &dma_spec))
+ return -ENODEV;
+
+ if (dma_spec.args_count)
+ return dma_spec.args[0];
+
+ return -ENODEV;
+}

Much cleaner!

+
+/* Initialize the dml hardware connected to SD Card controller */
+int dml_hw_init(struct mmci_host *host, struct device_node *np)
+{
+ u32 config;
+ void __iomem *base;
+ u32 consumer_id, producer_id;
+
+ consumer_id = of_get_dml_pipe_index(np, "tx");
+ producer_id = of_get_dml_pipe_index(np, "rx");
+
+ if (producer_id < 0 || consumer_id < 0)
+ return -ENODEV;
+
+ base = host->base + DML_OFFSET;
+
+ /* Reset the DML block */
+ writel_relaxed(1, base + DML_SW_RESET);
+
+ /* Disable the producer and consumer CRCI */
+ config = (PRODUCER_CRCI_DISABLE | CONSUMER_CRCI_DISABLE);
+ /*
+ * Disable the bypass mode. Bypass mode will only be used
+ * if data transfer is to happen in PIO mode and don't
+ * want the BAM interface to connect with SDCC-DML.
+ */
+ config &= ~BYPASS;
+ /*
+ * Disable direct mode as we don't DML to MASTER the AHB bus.
+ * BAM connected with DML should MASTER the AHB bus.
+ */
+ config &= ~DIRECT_MODE;
+ /*
+ * Disable infinite mode transfer as we won't be doing any
+ * infinite size data transfers. All data transfer will be
+ * of finite data size.
+ */
+ config &= ~INFINITE_CONS_TRANS;
+ writel_relaxed(config, base + DML_CONFIG);
+
+ /*
+ * Initialize the logical BAM pipe size for producer
+ * and consumer.
+ */
+ writel_relaxed(PRODUCER_PIPE_LOGICAL_SIZE,
+ base + DML_PRODUCER_PIPE_LOGICAL_SIZE);
+ writel_relaxed(CONSUMER_PIPE_LOGICAL_SIZE,
+ base + DML_CONSUMER_PIPE_LOGICAL_SIZE);
+
+ /* Initialize Producer/consumer pipe id */
+ writel_relaxed(producer_id | (consumer_id << CONSUMER_PIPE_ID_SHFT),
+ base + DML_PIPE_ID);
+

We have an mb() here too. Not sure why though. There's lots of comments
downstream but not where it actually would help!
I will add mb here and try to add some comments here.



+ return 0;
+}
diff --git a/drivers/mmc/host/mmci_qcom_dml.h b/drivers/mmc/host/mmci_qcom_dml.h
new file mode 100644
index 0000000..412e9a3
--- /dev/null
+++ b/drivers/mmc/host/mmci_qcom_dml.h
@@ -0,0 +1,31 @@
+/*
+ *
+ * Copyright (c) 2014, Code Aurora Forum. All rights reserved.

Hmm I see:

Copyright (c) 2011, The Linux Foundation. All rights reserved.

in these files. Can you use that?
https://git.linaro.org/landing-teams/working/qualcomm/kernel.git/blob/refs/heads/inforce/ifc6410/v1.5:/drivers/mmc/host/msm_sdcc_dml.c
in 3.4 kernel has:

Copyright (c) 2011, Code Aurora Forum. All rights reserved.

Do you still want to add Linux Foundation copyright in it.

thanks,
srini

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