Hi Andy.

Thanks for the review and sorry for the late reply.

-----Original Message-----
From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Sent: Monday, November 9, 2020 7:41 PM
To: Wan Mohamad, Wan Ahmad Zainie
[off-list ref]
Cc: kishon@ti.com; vkoul@kernel.org; robh+dt@kernel.org; linux-
kernel@vger.kernel.org; devicetree@vger.kernel.org;
mgross@linux.intel.com; Raja Subramanian, Lakshmi Bai
[off-list ref]
Subject: Re: [PATCH v2 2/2] phy: intel: Add Keem Bay USB PHY support

On Mon, Nov 09, 2020 at 11:16:54AM +0800, Wan Ahmad Zainie wrote:

quoted

Add support for USB PHY on Intel Keem Bay SoC.

...

quoted

+config PHY_INTEL_KEEMBAY_USB
+	tristate "Intel Keem Bay USB PHY driver"
+	depends on ARCH_KEEMBAY || (ARM64 && COMPILE_TEST)

quoted

+	depends on OF && HAS_IOMEM

Do you really need dependency to OF (yes, I see that it will be not functional,
but still can be compile tested)?

No, I can drop OF.
I will remove in v3.

quoted

+	select GENERIC_PHY
+	select REGMAP_MMIO
+	help
+	  Choose this option if you have an Intel Keem Bay SoC.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called phy-keembay-usb.ko.

...

quoted

+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/module.h>

quoted

+#include <linux/of.h>

No evidence of anything being used in this code.
mod_devicetable.h is missed, though.

I will fix in v3. Remove of.h and add mod_devicetable.h.

quoted

+#include <linux/phy/phy.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>

...

quoted

+	usleep_range(30, 50);

Why 30-50?

I take this value from boot firmware.
There is a delay of 30us after clearing IDDQ_enable bit.
I believe the purpose is to ensure all analog blocks are powered up.

...

quoted

+	usleep_range(20, 50);

Why these numbers?

In Keem Bay data book, under USB initialization section,
there is step that there must be a minimum 20us wait
after clock enable, before bringing PHYs out of reset.

50 is the value that I picked randomly. Is usleep_range(20, 20)
Better?

...

quoted

+	usleep_range(2, 10);

Ditto.

Under the same section above, there is a step for 2us wait.
I believe it is for register write to go through.

...

quoted

+	usleep_range(20, 50);

Ditto.

Under the same section above, there is a step to wait 20us
after setting SRAM load bit, before release the controller
reset.

I will add comment for those 4 delay above.

Before I proceed with v3, I would like to know if I should
use udelay(), instead of usleep_range()?
I refer to https://www.kernel.org/doc/Documentation/timers/timers-howto.txt.

...

quoted

+	struct device_node *np = dev->of_node;

It's being used only once and it doesn't bring any benefit.

I will fix in v3. Use dev->of_node directly.

--
With Best Regards,
Andy Shevchenko

Best regards,
Zainie