Hi Mark,

On Thu, Feb 07, 2013 at 16:16:56, Mark Rutland wrote:

Hello,

I have a couple of comments on the dt bindings and the way it's parsed.

Thanks for your review comments.

On Thu, Feb 07, 2013 at 07:57:04AM +0000, Manjunathappa, Prakash wrote:

quoted

Adds device tree support for davinci_mmc. Also add binding documentation.
Tested in non-dma PIO mode and without GPIO card_detect/write_protect
option because of dependencies on EDMA and GPIO module DT support.

Signed-off-by: Manjunathappa, Prakash <redacted>
Cc: linux-mmc@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Cc: davinci-linux-open-source@linux.davincidsp.com
Cc: devicetree-discuss@lists.ozlabs.org
Cc: cjb@laptop.org
Cc: Sekhar Nori <redacted>
Cc: mporter@ti.com
---
Since v1:
Modified DT parse function to take default values and accomodate controller
version in compatible field.

 .../devicetree/bindings/mmc/davinci_mmc.txt        |   30 ++++++++
 drivers/mmc/host/davinci_mmc.c                     |   70 +++++++++++++++++++-
 2 files changed, 99 insertions(+), 1 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/mmc/davinci_mmc.txt

diff --git a/Documentation/devicetree/bindings/mmc/davinci_mmc.txt b/Documentation/devicetree/bindings/mmc/davinci_mmc.txt
new file mode 100644
index 0000000..6717ab1
--- /dev/null
+++ b/Documentation/devicetree/bindings/mmc/davinci_mmc.txt

@@ -0,0 +1,30 @@
+* TI Highspeed MMC host controller for DaVinci
+
+The Highspeed MMC Host Controller on TI DaVinci family
+provides an interface for MMC, SD and SDIO types of memory cards.
+
+This file documents the properties used by the davinci_mmc driver.
+
+Required properties:
+- compatible:
+ Should be "ti,davinci-mmc-da830": for da830, da850, dm365
+ Should be "ti,davinci-mmc-dm355": for dm355, dm644x
+
+Optional properties:
+- bus-width: Number of data lines, can be <4>, or <8>, default <1>
+- max-frequency: Maximum operating clock frequency, default 25MHz.
+- mmc-cap-mmc-highspeed: Indicates support for MMC in high speed mode
+- mmc-cap-sd-highspeed: Indicates support for SD in high speed mode

I thought the last two were derivable from max-frequency?

Yes, but I see below comment that it doesnot support MMC/SD.
arch/arm/mach-davinci/devices.c: davinci_setup_mmc
	   "
         * FIXME dm6441 (no MMC/SD), dm357 (one), and dm335 (two) are
         * not handled right here ...
         */"
I was wondering how do we support such platforms, so I thought it is necessary
to have these. But I see that on da850-evm even on skipping above flags EVM is able
to detect card, does it mean there is no way to specify "no SD/MMC" capability?
I will remove these and decide highspeed capability based on max-frequency.

https://lkml.org/lkml/2012/10/15/231

[...]

quoted

+static struct davinci_mmc_config
+	*mmc_parse_pdata(struct platform_device *pdev)
 {
+	struct device_node *np;
 	struct davinci_mmc_config *pdata = pdev->dev.platform_data;
+	const struct of_device_id *match =
+		of_match_device(of_match_ptr(davinci_mmc_dt_ids), &pdev->dev);
+	u32 data;
+
+	np = pdev->dev.of_node;
+	if (!np)
+		return pdata;
+
+	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
+	if (!pdata) {
+		dev_err(&pdev->dev, "Failed to allocate memory for struct davinci_mmc_config\n");
+		goto nodata;
+	}
+
+	if (match->data)
+		pdata->version = (u8)((int)match->data);
+
+	of_property_read_u32(np, "max-frequency", &pdata->max_freq);
+	if (!pdata->max_freq)
+		dev_info(&pdev->dev, "'max-frequency' property not specified, defaulting to 25MHz\n");
+
+	if (of_get_property(np, "mmc-cap-mmc-highspeed", NULL))
+		pdata->caps |= MMC_CAP_MMC_HIGHSPEED;
+	if (of_get_property(np, "mmc-cap-sd-highspeed", NULL))
+		pdata->caps |= MMC_CAP_SD_HIGHSPEED;

If these aren't derivable from max-frequency, you could use
of_property_read_bool to make this clearer.

Correct, I will decide these based on max-frequency.

quoted

+
+	of_property_read_u32(np, "bus-width", &data);
+	switch (data) {
+	case 0:

Judging by the binding doc, should this be 1 rather than 0?

By default driver comes up in 4 bit mode when bus-width is not specified.
Bus-width is set to 1 bit for invalid bus-widths. Below are the cases
when bus-width 0 or 4, bus-width is set to 4bit mode
When bus-width is 8, bus-width is set to 8 bit mode

I thought that if somebody specifies bus-width as 2, 3, 5, 6, 7..., then
it should be defaulted to 1 bit mode, so I specified it as 1 bit in binding doc.
But I feel that a person who is editing dts file will not make such a mistake.
I will change binding document to default as 4 bit mode.

quoted

+	case 4:
+	case 8:
+		pdata->wires = data;
+		break;
+	default:
+		pdata->wires = 1;
+		dev_info(&pdev->dev, "Unsupported buswidth, defaulting to 1 bit\n");
+	}
+nodata:
+	return pdata;
+}
+
+static int __init davinci_mmcsd_probe(struct platform_device *pdev)
+{
+	struct davinci_mmc_config *pdata = NULL;
 	struct mmc_davinci_host *host = NULL;
 	struct mmc_host *mmc = NULL;
 	struct resource *r, *mem = NULL;
 	int ret = 0, irq = 0;
 	size_t mem_size;
 
+	pdata = mmc_parse_pdata(pdev);
+	if (pdata == NULL) {
+		dev_err(&pdev->dev, "Can not get platform data\n");
+		return -ENOENT;
+	}
+
 	/* REVISIT:  when we're fully converted, fail if pdata is NULL */

This comment can presumably disappear judging by the lines above?

Agreed. I will remove it.

Thanks,
Prakash