[PATCH V4 02/25] mmc: mmci: create generic mmci_dma_setup

From: Ulf Hansson <hidden>
Date: 2018-10-03 09:22:44
Also in: linux-devicetree, linux-mmc, lkml

+ Srinivas

[...]

quoted hunk

 #ifdef CONFIG_DMA_ENGINE
-static void mmci_dma_setup(struct mmci_host *host)
+static inline void mmci_dma_release(struct mmci_host *host);
+
+int mmci_dmae_setup(struct mmci_host *host)
 {
        const char *rxname, *txname;

@@ -464,8 +485,12 @@ static void mmci_dma_setup(struct mmci_host *host)
                        host->mmc->max_seg_size = max_seg_size;
        }

-       if (host->ops && host->ops->dma_setup)
-               host->ops->dma_setup(host);
+       if (!host->dma_tx_channel || !host->dma_rx_channel) {
+               mmci_dma_release(host);

This doesn't look right to me. The existing code allows a tx channel
to be used, even if an rx channel could not be setup. It seems
reasonable to still allow that.

quoted hunk

+               return -EINVAL;
+       }
+
+       return 0;
 }

 /*

@@ -496,7 +521,7 @@ static void mmci_dma_unmap(struct mmci_host *host, struct mmc_data *data)

 static void mmci_dma_data_error(struct mmci_host *host)
 {
-       if (!dma_inprogress(host))
+       if (!host->use_dma || !dma_inprogress(host))

Adding the check for use_dma here seems like an unnecessary check,
unless there is a reason for it due to following changes on top. In
such case, please make it a part of the patch(es) where it's actually
needed.

quoted hunk

                return;

        dev_err(mmc_dev(host->mmc), "error during DMA transfer!\n");

@@ -514,7 +539,7 @@ static void mmci_dma_finalize(struct mmci_host *host, struct mmc_data *data)
        u32 status;
        int i;

-       if (!dma_inprogress(host))
+       if (!host->use_dma || !dma_inprogress(host))

Ditto.

quoted hunk

                return;

        /* Wait up to 1ms for the DMA to complete */

@@ -546,6 +571,7 @@ static void mmci_dma_finalize(struct mmci_host *host, struct mmc_data *data)
        if (status & MCI_RXDATAAVLBLMASK) {
                dev_err(mmc_dev(host->mmc), "buggy DMA detected. Taking evasive action.\n");
                mmci_dma_release(host);
+               host->use_dma = false;
        }

        host->dma_in_progress = false;
@@ -640,6 +666,9 @@ static int mmci_dma_start_data(struct mmci_host *host, unsigned int datactrl)
        int ret;
        struct mmc_data *data = host->data;

+       if (!host->use_dma)
+               return -EINVAL;
+
        ret = mmci_dma_prep_data(host, host->data);
        if (ret)
                return ret;
@@ -674,6 +703,9 @@ static void mmci_get_next_data(struct mmci_host *host, struct mmc_data *data)
 {
        struct mmci_host_next *next = &host->next_data;

+       if (!host->use_dma)
+               return;
+
        WARN_ON(data->host_cookie && data->host_cookie != next->cookie);
        WARN_ON(!data->host_cookie && (next->dma_desc || next->dma_chan));
@@ -689,7 +721,7 @@ static void mmci_pre_request(struct mmc_host *mmc, struct mmc_request *mrq)
        struct mmc_data *data = mrq->data;
        struct mmci_host_next *nd = &host->next_data;

-       if (!data)
+       if (!host->use_dma || !data)
                return;

        BUG_ON(data->host_cookie);
@@ -707,7 +739,7 @@ static void mmci_post_request(struct mmc_host *mmc, struct mmc_request *mrq,
        struct mmci_host *host = mmc_priv(mmc);
        struct mmc_data *data = mrq->data;

-       if (!data || !data->host_cookie)
+       if (!host->use_dma || !data || !data->host_cookie)

Ditto.

quoted hunk

                return;

        mmci_dma_unmap(host, data);

@@ -735,14 +767,14 @@ static void mmci_post_request(struct mmc_host *mmc, struct mmc_request *mrq,
        }
 }

+static struct mmci_host_ops mmci_variant_ops = {
+       .dma_setup = mmci_dmae_setup,
+};
 #else
 /* Blank functions if the DMA engine is not available */
 static void mmci_get_next_data(struct mmci_host *host, struct mmc_data *data)
 {
 }
-static inline void mmci_dma_setup(struct mmci_host *host)
-{
-}

 static inline void mmci_dma_release(struct mmci_host *host)
 {
@@ -765,8 +797,14 @@ static inline int mmci_dma_start_data(struct mmci_host *host, unsigned int datac
 #define mmci_pre_request NULL
 #define mmci_post_request NULL

+static struct mmci_host_ops mmci_variant_ops = {};

This seems a bit unnecessary. See more about why, below.

 #endif

+void mmci_variant_init(struct mmci_host *host)

Looks like you should make mmci_variant_init() internal to mmci.c,
thus covert it to static.

Moreover, I suggest you define a "static inline void
mmci_variant_init()", when CONFIG_DMA_ENGINE is unset. In that way you
don't need to assign host->ops at all for this case.

quoted hunk

+{
+       host->ops = &mmci_variant_ops;
+}
+
 static void mmci_start_data(struct mmci_host *host, struct mmc_data *data)
 {
        struct variant_data *variant = host->variant;

diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h
index 01e6c6b..f7fe80f 100644
--- a/drivers/mmc/host/mmci.h
+++ b/drivers/mmc/host/mmci.h

@@ -273,7 +273,7 @@ struct variant_data {

 /* mmci variant callbacks */
 struct mmci_host_ops {
-       void (*dma_setup)(struct mmci_host *host);
+       int (*dma_setup)(struct mmci_host *host);
 };

 struct mmci_host_next {

@@ -323,6 +323,7 @@ struct mmci_host {
        unsigned int            size;
        int (*get_rx_fifocnt)(struct mmci_host *h, u32 status, int remain);

+       u8                      use_dma:1;
 #ifdef CONFIG_DMA_ENGINE
        /* DMA stuff */
        struct dma_chan         *dma_current;

@@ -336,3 +337,7 @@ struct mmci_host {
 #endif
 };

+void mmci_variant_init(struct mmci_host *host);
+
+int mmci_dmae_setup(struct mmci_host *host);
+

diff --git a/drivers/mmc/host/mmci_qcom_dml.c b/drivers/mmc/host/mmci_qcom_dml.c
index be3fab5..c8d7592 100644
--- a/drivers/mmc/host/mmci_qcom_dml.c
+++ b/drivers/mmc/host/mmci_qcom_dml.c

@@ -119,19 +119,22 @@ static int of_get_dml_pipe_index(struct device_node *np, const char *name)
 }

 /* Initialize the dml hardware connected to SD Card controller */
-static void qcom_dma_setup(struct mmci_host *host)
+static int qcom_dma_setup(struct mmci_host *host)
 {
        u32 config;
        void __iomem *base;
        int consumer_id, producer_id;
        struct device_node *np = host->mmc->parent->of_node;

+       if (mmci_dmae_setup(host))
+               return -EINVAL;
+
        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) {
                host->variant->qcom_dml = false;
-               return;
+               return -EINVAL;

Seems like you need to call a corresponding dma release function here,
before returning the error code.

Probably an "mmci_dmae_release()" needs to be implemented as a part of
this change - and then also called from here. This is according to
Srinivas recommendations, which means falling back to pio. As a matter
of fact this also needs to be clearly stated in the changelog, as you
are really also improving the behavior for the Qcom variant.

Unfortunate, I am not able to test this as I don't have the HW (which
I thought I had). Perhaps Srinivas can help, once we have something
ready for him to test.

quoted hunk

        }

        base = host->base + DML_OFFSET;

@@ -175,6 +178,8 @@ static void qcom_dma_setup(struct mmci_host *host)

        /* Make sure dml initialization is finished */
        mb();
+
+       return 0;
 }

 static struct mmci_host_ops qcom_variant_ops = {
--

2.7.4

Kind regards
Uffe

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