[U-Boot] [PATCH V4] I2C: mxc_i2c rework

[Jason Hui]

On Wed, Aug 10, 2011 at 1:59 PM, Marek Vasut <marek.vasut at gmail.com> wrote:
> On Saturday, July 30, 2011 12:52:53 PM Marek Vasut wrote:
>> On Saturday, July 30, 2011 08:42:19 AM Jason Hui wrote:
>> > Hi, Marek,
>> >
>> > On Sat, Jul 30, 2011 at 1:09 AM, Marek Vasut <marek.vasut at gmail.com> wrote:
>> > > On Friday, July 29, 2011 01:24:49 PM Jason Hui wrote:
>> > >> Hi, Marek,
>> > >>
>> > >> On Fri, Jul 29, 2011 at 5:32 PM, Marek Vasut <marek.vasut at gmail.com>
> wrote:
>> > >> > Rewrite the mxc_i2c driver.
>> > >> >
>> > >> >  * This version is much closer to Linux implementation.
>> > >> >  * Fixes IPG_PERCLK being incorrectly used as clock source
>> > >> >  * Fixes behaviour of the driver on iMX51
>> > >> >  * Clean up coding style a bit ;-)
>> > >>
>> > >> I don't think you did the right thing by chaning IPG_PERCLK to IPG_CLK
>> > >> As I said, the IPG_CLK is for IP register clock, while IPG_PERCLK is
>> > >> for i2c function clock.
>> > >>
>> > >> if you run clock command from mx51evk, you will get:
>> > >> ...
>> > >> ipg clock     : 66500000Hz
>> > >> ipg per clock : 665000000Hz
>> > >> MX51EVK U-Boot >
>> > >>
>> > >> It will give you that ipg per clock is 665M, which seems too big. It
>> > >> is due to we configure
>> > >> the pre-divider/pos-devider for perclk to zero, which leads to ipg_per
>> > >> clock to be same as pll2 clock.
>> > >> But I don't think this will have some issue.
>> > >
>> > > Yes it will, the divider will be computed to be maximum in all cases
>> > > ... you won't be able it divide 665MHz by anything from the table 40-7
>> > > in MX51RM to achieve any reasonable frequency.
>> > >
>> > > On the contrary, 66.5MHz does give fine results.
>> >
>> > it that, we can change the ipg_perclk to low freq, but we should not
>> > change the i2c clock to ipg_clk, this is not correct.
>> >
>> > >> BTW, I have applied your patch and test on mx53evk board, it seems the
>> > >> i2c does not work correctly.
>> > >
>> > > Great. The clock used by the I2C module for this task are likely the
>> > > module_clock, which are -- like on MX51 -- 66.5MHz. What do you get
>> > > when you run the "clock" command on MX53EVK ?
>> >
>> > I'm not in the office for the whole next week, thus, I can't give you
>> > the clock output for
>> > mx53evk, but I'm sure the ipg_perclk on mx53evk is not set at 66.5Mhz.
>>
>> Yes, it's 33.3MHz on iMX53. I got a (remote) hand of a MX53 board. The IPG
>> clock, on the other hand, are 66.5MHz on both MX51 and MX53. Maybe the
>> issue with PMIC you're seeing is something else?
>>
>> btw. how did you obtain these results ? Can you check the FDR divider value
>> with and without this patch?

You can use the clock command to get it. As for the FDR, you want me to check it
on i.mx53evk board right?

Jason

>>
>> Thanks
>
>
>>
>> > Jason
>> >
>> > > Thanks
>> > >
>> > >> After apply your patch:
>> > >> MX53EVK U-Boot > pmic dump  30
>> > >> PMIC ID: 0x0000ffff [Rev: unknown]
>> > >>
>> > >> 0x00: 0001ffff 00ffffff 0039ffff 0000ffff 00ffffff 0000ffff 0000ffff
>> > >> 0000ffff 0x08: 0000ffff 0000ffff 0000ffff 0000ffff 0000ffff 0000ffff
>> > >> 0000ffff 0040ffff 0x10: 0000ffff 0000ffff 0000ffff 0000ffff 0000ffff
>> > >> 0001ffff 0000ffff 0000ffff 0x18: 0045ffff 0045ffff 0000ffff 0080ffff
>> > >> 0021ffff 0000ffff 0002ffff 0000ffff 0x20: 0004ffff 0000ffff 0021ffff
>> > >> 0000ffff 0000ffff 0000ffff 0000ffff 0000ffff 0x28: 0000ffff 0000ffff
>> > >> 0000ffff 0000ffff 0000ffff 0004ffff 0000ffff 00aeffff
>> > >>
>> > >> The old:
>> > >> MX53EVK U-Boot > pmic dump 30
>> > >> PMIC ID: 0x000045d0 [Rev: 2.0]
>> > >>
>> > >> 0x00: 00015088 00ffffff 00395208 00000081 00fff7ff 0000401c 00000418
>> > >> 000045d0 0x08: 00000000 00000000 00000001 00000000 00000000 00000040
>> > >> 00000000 00400000 0x10: 00000000 00000000 00000000 00000000 00000011
>> > >> 0001ffff 00000000 00007fff 0x18: 00454a52 00456739 0000631a 0080739c
>> > >> 0021284a 00000a0a 00024fd0 000001d8 0x20: 00049208 00000000 00218000
>> > >> 00000000 00000000 00000000 00000000 00000000 0x28: 00000000 00000000
>> > >> 00000000 00008000 00000000 00046046 000001c0 00aeeaee
>> > >>
>> > >> Jason
>