Re: [PATCH 1/4] phy: Add provision for calibrating phy.

[Vivek Gautam <gautam.vivek@samsung.com>]

Hi,


On Mon, Jun 9, 2014 at 9:19 AM, Pratyush Anand <pratyush.anand@st.com> wrote:
> On Fri, Jun 06, 2014 at 08:12:12PM +0800, Vivek Gautam wrote:
>> Some PHY controllers may need to calibrate certain
>> PHY settings after initialization of the controller and
>> sometimes even after initializing the PHY-consumer too.
>> Add support for the same in order to let consumers do so in need.
>>
>> Signed-off-by: vivek Gautam <gautam.vivek@samsung.com>
>> ---
>>  drivers/phy/phy-core.c  |   36 ++++++++++++++++++++++++++++++++++++
>>  include/linux/phy/phy.h |    7 +++++++
>>  2 files changed, 43 insertions(+)
>>
>> diff --git a/drivers/phy/phy-core.c b/drivers/phy/phy-core.c
>> index 74d4346..92d31a3 100644
>> --- a/drivers/phy/phy-core.c
>> +++ b/drivers/phy/phy-core.c
>> @@ -376,6 +376,42 @@ int phy_power_off(struct phy *phy)
>>  EXPORT_SYMBOL_GPL(phy_power_off);
>>
>>  /**
>> + * phy_calibrate - calibrate a phy post initialization
>> + * @phy: Pointer to 'phy' from consumer
>> + *
>> + * For certain PHYs, it may be needed to calibrate few phy parameters
>> + * post initialization. The need to calibrate may arise after the
>
> For USB you may need to calibrate phy after each new connection. If
> so, why not to use already existing struct usb_phy's notify_connect.

The phy_calibrate will rather be a one time phenomenon.
On exynos atleast the case is : the phy settings for PIPE3 phy on DWC3
controller need to be
configured post hcd reset. so that we don't need to re-configure these
phy settings on every connect.

Moreover *there are certain devices* which need these PHY settings
even to show a connect-status-change.
So, it would rather be not useful to create a 'phy_notify_connect' API
in drivers/phy/ and use the same for this purpose.



-- 
Best Regards
Vivek Gautam
Samsung R&D Institute, Bangalore
India