Re: [PATCH v3] USB: PHY: Palmas USB Transceiver Driver

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On Tuesday 26 March 2013 03:51 PM, Felipe Balbi wrote:
* PGP Signed by an unknown key

Hi,

On Tue, Mar 26, 2013 at 09:01:42AM +0000, Graeme Gregory wrote:
From: Graeme Gregory <gg@xxxxxxxxxxxxxxx>

This is the driver for the OTG transceiver built into the Palmas
chip. It
handles the various USB OTG events that can be generated by cable
insertion/removal.

Signed-off-by: Graeme Gregory <gg@xxxxxxxxxxxxxxx>
Signed-off-by: Moiz Sonasath <m-sonasath@xxxxxx>
Signed-off-by: Ruchika Kharwar <ruchika@xxxxxx>
Signed-off-by: Kishon Vijay Abraham I <kishon@xxxxxx>
Signed-off-by: Sebastien Guiriec <s-guiriec@xxxxxx>
---
I think this driver is more over the cable connection like vbus
detetcion or ID pin detection.
Then why not it is implemented based on extcon framework?
extcon framework uses notification mechanism and Felipe dint like
using notification here. right Felipe?
That way, generic usb driver (like tegra_usb driver) will get
notification through extcon.

We need this cable detection through extcon on our tegra solution
through the Palmas.


+#include <linux/of.h>
+#include <linux/of_platform.h>
+
+static int palmas_usb_read(struct palmas *palmas, unsigned int reg,
+               unsigned int *dest)
+{
+       unsigned int addr;
+       int slave;
+
+       slave = PALMAS_BASE_TO_SLAVE(PALMAS_USB_OTG_BASE);
+       addr = PALMAS_BASE_TO_REG(PALMAS_USB_OTG_BASE, reg);
+
+       return regmap_read(palmas->regmap[slave], addr, dest);


Please use the generic api for palmas_read()/palmas_write(0 as it will
be ease on debugging on register access.
Direct regmap_read() does not help much on this.
Graeme,
Any reason why you dint use palmas_read()/palmas_write here?
Btw palmas_read()/palmas_write() internally uses regmap APIs.
Because I was not a fan of tightly coupling the child devices to the
parent MFD. palmas_read/write were added by Laxman.
I guess regmap would also help abstracting SPI versus I2C connection.
IMHO, palmas_read/write should be removed.

Laxman's complaint that it doesn't help with debugging is utter
nonsense.
palams read/write api uses the regmap only and hence not break anything on abstraction. in place of doing the following three statement in whole word, it provides wrapper of palmas_read()
which actually does the same.

slave = PALMAS_BASE_TO_SLAVE(PALMAS_USB_OTG_BASE);
addr = PALMAS_BASE_TO_REG(PALMAS_USB_OTG_BASE, reg);

regmap_read(palmas->regmap[slave], addr, dest);

Above 3 lines in all the places for resgister access or make single call:
palmas_read(palmas, PALMAS_USB_OTG_BASE, PALMAS_USB_OTG_BASE, dest).

This function implement the above 3 lines.


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