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Date: Mon, 14 Jan 2013 13:36:49 +0530
From: Vivek Gautam <gautamvivek1987@...il.com>
To: Doug Anderson <dianders@...omium.org>
Cc: Vivek Gautam <gautam.vivek@...sung.com>, linux-usb@...r.kernel.org,
yulgon.kim@...sung.com, linux-samsung-soc@...r.kernel.org,
Praveen Paneri <p.paneri@...sung.com>,
gregkh@...uxfoundation.org, devicetree-discuss@...ts.ozlabs.org,
jg1.han@...sung.com,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
balbi@...com, kishon@...com, Kukjin Kim <kgene.kim@...sung.com>,
Alan Stern <stern@...land.harvard.edu>,
Rob Herring <rob.herring@...xeda.com>,
Sylwester Nawrocki <sylvester.nawrocki@...il.com>
Subject: Re: [PATCH v5 2/4] usb: phy: samsung: Add host phy support to
samsung-phy driver
Hi Doug,
On Mon, Jan 14, 2013 at 11:15 AM, Vivek Gautam
<gautamvivek1987@...il.com> wrote:
> Hi Doug,
>
>
> On Sat, Jan 12, 2013 at 6:20 AM, Doug Anderson <dianders@...omium.org> wrote:
>> Vivek,
>>
>> On Fri, Jan 11, 2013 at 4:40 AM, Vivek Gautam <gautamvivek1987@...il.com> wrote:
>>>>> +#define HOST_CTRL0_REFCLKSEL_MASK (0x3)
>>>>> +#define HOST_CTRL0_REFCLKSEL_XTAL (0x0 << 19)
>>>>> +#define HOST_CTRL0_REFCLKSEL_EXTL (0x1 << 19)
>>>>> +#define HOST_CTRL0_REFCLKSEL_CLKCORE (0x2 << 19)
>>>>> +
>>>>> +#define HOST_CTRL0_FSEL_MASK (0x7 << 16)
>>>>> +#define HOST_CTRL0_FSEL(_x) ((_x) << 16)
>>>>> +#define HOST_CTRL0_FSEL_CLKSEL_50M (0x7)
>>>>> +#define HOST_CTRL0_FSEL_CLKSEL_24M (0x5)
>>>>> +#define HOST_CTRL0_FSEL_CLKSEL_20M (0x4)
>>>>> +#define HOST_CTRL0_FSEL_CLKSEL_19200K (0x3)
>>>>> +#define HOST_CTRL0_FSEL_CLKSEL_12M (0x2)
>>>>> +#define HOST_CTRL0_FSEL_CLKSEL_10M (0x1)
>>>>> +#define HOST_CTRL0_FSEL_CLKSEL_9600K (0x0)
>>>>
>>>> Add the shifts to the #defines and remove HOST_CTRL0_FSEL(_x). That
>>>> makes it match the older phy more closely.
>>>>
>>> Wouldn't it hamper the readability when shifts are used ??
>>> I mean if we have something like this -
>>>
>>> phyhost |= HOST_CTRL0_FSEL(phyclk)
>>>
>>> so, if we are using the shifts then
>>> phyhost |= (HOST_CTRL0_FSEL_CLKSEL_24M << HOST_CTRL0_FSEL_SHIFT)
>>
>> I was actually suggesting modifying the #defines like this:
>>
>> #define HOST_CTRL0_FSEL_SHIFT 16
>> #define HOST_CTRL0_FSEL_MASK (0x7 << HOST_CTRL0_FSEL_SHIFT)
>> #define HOST_CTRL0_FSEL_CLKSEL_50M (0x7 << HOST_CTRL0_FSEL_SHIFT)
>> #define HOST_CTRL0_FSEL_CLKSEL_24M (0x5 << HOST_CTRL0_FSEL_SHIFT)
>> #define HOST_CTRL0_FSEL_CLKSEL_20M (0x4 << HOST_CTRL0_FSEL_SHIFT)
>> #define HOST_CTRL0_FSEL_CLKSEL_19200K (0x3 << HOST_CTRL0_FSEL_SHIFT)
>> #define HOST_CTRL0_FSEL_CLKSEL_12M (0x2 << HOST_CTRL0_FSEL_SHIFT)
>> #define HOST_CTRL0_FSEL_CLKSEL_10M (0x1 << HOST_CTRL0_FSEL_SHIFT)
>> #define HOST_CTRL0_FSEL_CLKSEL_9600K (0x0 << HOST_CTRL0_FSEL_SHIFT)
>>
>> ...then the code doesn't need to think about shifts, right?
>>
>
> right right, sorry i din't get your point earlier. :-(
>
> this way things will be similar in samsung_usbphy_get_refclk_freq()
> across exynos 5 and older SoCs.
>
> Is it fine if we don't use macro for SHIFT, earlier code also doesn't use it.
> Can we just do like this ..
> #define HOST_CTRL0_FSEL_MASK (0x7 << 16)
> #define HOST_CTRL0_FSEL_CLKSEL_50M (0x7 << 16)
> #define HOST_CTRL0_FSEL_CLKSEL_24M (0x5 << 16)
> #define HOST_CTRL0_FSEL_CLKSEL_20M (0x4 << 16)
> #define HOST_CTRL0_FSEL_CLKSEL_19200K (0x3 << 16)
> #define HOST_CTRL0_FSEL_CLKSEL_12M (0x2 << 16)
> #define HOST_CTRL0_FSEL_CLKSEL_10M (0x1 << 16)
> #define HOST_CTRL0_FSEL_CLKSEL_9600K (0x0 << 16)
>
Actually missed one thing here, this "HOST_CTRL0_FSEL_CLKSEL_XX" is
being used by
HOST/OTG blocks to prepare reference clock, that's the reason we kept
#define HOST_CTRL0_FSEL(_x) ((_x) << 16)
and #define OTG_SYS_FSEL(_x) ((_x) << 4)
where (_x) is the reference clock returned from
samsung_usbphy_get_refclk_freq().
So in order to avoid confusion we can change the macro names only and
keep something like
#define HOST_CTRL0_FSEL_MASK (0x7 << 16)
#define HOST_CTRL0_FSEL(_x) ((_x) << 16)
#define FSEL_CLKSEL_50M (0x7)
#define FSEL_CLKSEL_24M (0x5)
#define FSEL_CLKSEL_20M (0x4)
#define FSEL_CLKSEL_19200K (0x3)
#define FSEL_CLKSEL_12M (0x2)
#define FSEL_CLKSEL_10M (0x1)
#define FSEL_CLKSEL_9600K (0x0)
...
#define OTG_SYS_FSEL_MASK (0x7 << 4)
#define OTG_SYS_FSEL(_x) ((_x) << 4)
>>
>>>>> if (IS_ERR(ref_clk)) {
>>>>> dev_err(sphy->dev, "Failed to get reference clock\n");
>>>>> return PTR_ERR(ref_clk);
>>>>> }
>>>>>
>>>>> - switch (clk_get_rate(ref_clk)) {
>>>>> - case 12 * MHZ:
>>>>> - refclk_freq = PHYCLK_CLKSEL_12M;
>>>>> - break;
>>>>> - case 24 * MHZ:
>>>>> - refclk_freq = PHYCLK_CLKSEL_24M;
>>>>> - break;
>>>>> - case 48 * MHZ:
>>>>> - refclk_freq = PHYCLK_CLKSEL_48M;
>>>>> - break;
>>>>> - default:
>>>>> - if (sphy->cpu_type == TYPE_S3C64XX)
>>>>> - refclk_freq = PHYCLK_CLKSEL_48M;
>>>>> - else
>>>>> + if (sphy->cpu_type == TYPE_EXYNOS5250) {
>>>>> + /* set clock frequency for PLL */
>>>>> + switch (clk_get_rate(ref_clk)) {
>>>>> + case 96 * 100000:
>>>>
>>>> nit: change to 9600 * KHZ to match; below too.
>>>>
>>> sure.
>>>
>>>>> + refclk_freq |= HOST_CTRL0_FSEL_CLKSEL_9600K;
>>>>
>>>> Why |= with 0?
>>>>
>>> kept this just to keep things look similar :-). will remove this line,
>>
>> My comment was about keeping things similar. Right now the 5250 code
>> has the |= and the non-5250 code doesn't. I don't care which is
>> picked but the two sides of the "if" should be symmetric.
>>
>
> True, it's good to maintain symmetry in the code.
> I shall amend the code as suggested.
>
And to maintain symmetry we can avoid putting |=
since refclk_freq is anyways initialized to 0, so this wouldn't make
any difference.
right ?
>> See parts of the patch below.
>>
>>>>> + break;
>>>>> + case 10 * MHZ:
>>>>> + refclk_freq |= HOST_CTRL0_FSEL_CLKSEL_10M;
>>>>> + break;
so we can change this to something like
case 10 * MHZ:
refclk_freq = FSEL_CLKSEL_10M;
break;
and so on.
will this be fine ?
>>>>> + case 12 * MHZ:
>>>>> + refclk_freq |= HOST_CTRL0_FSEL_CLKSEL_12M;
>>>>> + break;
>>>>> + case 192 * 100000:
>>>>> + refclk_freq |= HOST_CTRL0_FSEL_CLKSEL_19200K;
>>>>> + break;
>>>>> + case 20 * MHZ:
>>>>> + refclk_freq |= HOST_CTRL0_FSEL_CLKSEL_20M;
>>>>> + break;
>>>>> + case 50 * MHZ:
>>>>> + refclk_freq |= HOST_CTRL0_FSEL_CLKSEL_50M;
>>>>> + break;
>>>>> + case 24 * MHZ:
>>>>> + default:
>>>>> + /* default reference clock */
>>>>> + refclk_freq |= HOST_CTRL0_FSEL_CLKSEL_24M;
>>>>> + break;
>>>>> + }
>>>>> + } else {
>>>>> + switch (clk_get_rate(ref_clk)) {
>>>>> + case 12 * MHZ:
>>>>> + refclk_freq = PHYCLK_CLKSEL_12M;
>>>>> + break;
>>>>> + case 24 * MHZ:
>>>>> refclk_freq = PHYCLK_CLKSEL_24M;
>>>>> - break;
>>>>> + break;
>>>>> + case 48 * MHZ:
>>>>> + refclk_freq = PHYCLK_CLKSEL_48M;
>>>>> + break;
>>>>> + default:
>>>>> + if (sphy->cpu_type == TYPE_S3C64XX)
>>>>> + refclk_freq = PHYCLK_CLKSEL_48M;
>>>>> + else
>>>>> + refclk_freq = PHYCLK_CLKSEL_24M;
>>>>> + break;
>>>>> + }
>>>>> }
>>>>> clk_put(ref_clk);
>>>>>
>>>>> return refclk_freq;
>>>>> }
>>
--
Thanks & Regards
Vivek
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