Re: [PATCH V4 1/5] phy: Add new Exynos5 USB 3.0 PHY driver

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On 09.04.2014 13:49, Vivek Gautam wrote:
Hi,


On Wed, Apr 9, 2014 at 4:36 PM, Tomasz Figa <t.figa@xxxxxxxxxxx> wrote:
Hi Vivek,

Please see my comments inline.


On 08.04.2014 16:36, Vivek Gautam wrote:

Add a new driver for the USB 3.0 PHY on Exynos5 series of SoCs.
The new driver uses the generic PHY framework and will interact
with DWC3 controller present on Exynos5 series of SoCs.
Thereby, removing old phy-samsung-usb3 driver and related code
used untill now which was based on usb/phy framework.

Signed-off-by: Vivek Gautam <gautam.vivek@xxxxxxxxxxx>
---
   .../devicetree/bindings/phy/samsung-phy.txt        |   42 ++
   drivers/phy/Kconfig                                |   11 +
   drivers/phy/Makefile                               |    1 +
   drivers/phy/phy-exynos5-usbdrd.c                   |  668
++++++++++++++++++++
   4 files changed, 722 insertions(+)
   create mode 100644 drivers/phy/phy-exynos5-usbdrd.c


[snip]


+       Additional clock required for Exynos5420:
+       - usb30_sclk_100m: Additional special clock used for PHY operation
+                          depicted as 'sclk_usbphy30' in CMU of
Exynos5420.


Are you sure this isn't simply a gate for the ref clock, as it can be found
on another SoC that is not upstream yet? I don't have documentation for
Exynos 5420 so I can't tell, but I'd like to ask you to recheck this.

From what i can see in the manual :
sclk_usbphy30 is derived from OSCCLK.
It is coming from a MUX (default input line to this is OSCCLK)  and
then through a DIV
there's this gate.

       {OSCCLK  + other sources} --->[MUX] ---> [DIV] --> [GATE for
sclk_usbphy30]

the {rate of sclk_usbphy30} == OSCCLK

However the 'ref' clock that we have been using is the actual oscillator clock.
And on SoC Exynos5250, we don't have any such gate (sclk_usbphy30).
So should this mean that ref clock and sclk_usbphy30 are still be controlled by
two different gates ?


Is there maybe a diagram of PHY input clocks in the datasheet, like for USB 2.0 PHY in Exynos4210/4412/5250 datasheets in the chapter about USB2.0 Device? Something like:

                     ____________________________________
                    |                                    |
                    |                         ___________|
XusbXTI             |   Phy_fsel[2:0]        |  _______  |
   _______[X]_______|    |         __________|_|___|\__|_|
  |                 |   _v___     |  _____   ^ |   |/  | |
_____               |  |     |    | |     |  | |  ___  | |
 ___                |  |     |    | |     |  | | |   |_|_|
|___|               |  | X 0 |____|_| PLL |__|_|_|CLK|_|_|
_____               |  |     |      |     |    | |DIV|_|_|
  |_______[X]       |  |_____| 12   |_____|480 | |___| | |
                    |          MHz         MHz |Digital| |
XusbXTO             |   USB PHY                |_______| |
                    |____________________________________|


Best regards,
Tomasz
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