hi Ulf

On 09/24/2018 04:28 PM, Ulf Hansson wrote:

On 21 September 2018 at 11:45, Ludovic Barre [off-list ref] wrote:

quoted

From: Ludovic Barre <redacted>

This patch converts dma_setup callback to return an integer
This patch is needed to prepare sdmmc variant with internal dma

Signed-off-by: Ludovic Barre <redacted>
---
  drivers/mmc/host/mmci.c          | 14 ++++++++++----
  drivers/mmc/host/mmci.h          |  2 +-
  drivers/mmc/host/mmci_qcom_dml.c |  6 ++++--
  3 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
index cbd67bc..2f845f3 100644
--- a/drivers/mmc/host/mmci.c
+++ b/drivers/mmc/host/mmci.c

@@ -415,7 +415,7 @@ static void mmci_init_sg(struct mmci_host *host, struct mmc_data *data)
   * no custom DMA interfaces are supported.
   */
  #ifdef CONFIG_DMA_ENGINE
-static void mmci_dma_setup(struct mmci_host *host)
+static int mmci_dma_setup(struct mmci_host *host)
  {
         const char *rxname, *txname;

@@ -466,7 +466,9 @@ static void mmci_dma_setup(struct mmci_host *host)
         }

         if (host->ops && host->ops->dma_setup)
-               host->ops->dma_setup(host);
+               return host->ops->dma_setup(host);
+

Looks like you need to implement a error handling, instead of just
returning the error code.

yes, today if a dma_setup is defined, we can't fallback to pio mode.
A use_dma variable (defined in mmci_host) could be setted follow the 
return code of ops->dma_setup

example:

void mmci_dma_setup(struct mmci_host *host)
{
	int err;

	if (!host->ops || !host->ops->dma_setup)
		return;

	err = host->ops->dma_setup(host);
	if (err)
		return;
	
	host->use_dma = true;
	
	/* initialize pre request cookie */
	host->next_cookie = 1;
}

use_dma variable could be check by mmci_host_ops variant functions.

are you agree with this proposal?

quoted

+       return 0;
  }

  /*

@@ -741,8 +743,10 @@ static void mmci_post_request(struct mmc_host *mmc, struct mmc_request *mrq,
  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 int mmci_dma_setup(struct mmci_host *host)
  {
+       return 0;
  }

  static inline void mmci_dma_release(struct mmci_host *host)

@@ -1796,7 +1800,9 @@ static int mmci_probe(struct amba_device *dev,
                  amba_rev(dev), (unsigned long long)dev->res.start,
                  dev->irq[0], dev->irq[1]);

-       mmci_dma_setup(host);
+       ret = mmci_dma_setup(host);
+       if (ret)
+               goto clk_disable;

         pm_runtime_set_autosuspend_delay(&dev->dev, 50);
         pm_runtime_use_autosuspend(&dev->dev);

diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h
index 21aaf9a..06299ac 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 {

diff --git a/drivers/mmc/host/mmci_qcom_dml.c b/drivers/mmc/host/mmci_qcom_dml.c
index be3fab5..1bb59cf 100644
--- a/drivers/mmc/host/mmci_qcom_dml.c
+++ b/drivers/mmc/host/mmci_qcom_dml.c

@@ -119,7 +119,7 @@ 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;

@@ -131,7 +131,7 @@ static void qcom_dma_setup(struct mmci_host *host)

         if (producer_id < 0 || consumer_id < 0) {
                 host->variant->qcom_dml = false;

It seems like the existing code is an attempt to fallback to use pio
mode. However, I doubt it works as is.

oops, I seen that like a variant identification issue, so if it's a
fallback to pio mode it doesn't work.

quoted

-               return;
+               return -EINVAL;

My point is, if you return an error code here, it means that the error
code becomes propagated and ->probe() will fail.

Ideally, we should be able fall back to pio mode when dma doesn't
work. I have looped in Srinivas who implemented the qcom dml support,
let's see if he can explains the intent with the code.

I also volunteer to help out running some tests on the 410c platform,
however allow me a day or two to do that.

yes, I would be more reassured

quoted

         }

         base = host->base + DML_OFFSET;

@@ -175,6 +175,8 @@ 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