Messages in this thread | | | Date | Mon, 18 Jun 2012 09:41:00 +0100 | From | Lee Jones <> | Subject | Re: Fwd: [PATCH 1/3] i2c: Add Device Tree support to the Nomadik I2C driver |
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On 18/06/12 08:58, Srinidhi Kasagar wrote: > On Mon, Jun 18, 2012 at 09:18:05 +0200, Lee Jones wrote: >> On 17/06/12 18:43, Linus Walleij wrote: >>> Gah, what a thread... >>> >>> On Fri, Jun 15, 2012 at 3:18 PM, Lee Jones<lee.jones@linaro.org> wrote: >>>> On 15/06/12 14:05, Srinidhi Kasagar wrote: >>>>> On Fri, Jun 15, 2012 at 14:45:11 +0200, Lee Jones wrote: >>>>>> On 15/06/12 12:50, Srinidhi Kasagar wrote: >>> >>>>>>>> +static struct nmk_i2c_controller u8500_i2c = { >>>>>>>> + /* >>>>>>>> + * Slave data setup time; 250ns, 100ns, and 10ns, which >>>>>>>> + * is 14, 6 and 2 respectively for a 48Mhz i2c clock. >>>>>>>> + */ >>>>>>>> + .slsu = 0xe, >>>>>>>> + .tft = 1, /* Tx FIFO threshold */ >>>>>>>> + .rft = 8, /* Rx FIFO threshold */ >>>>>>>> + .clk_freq = 100000, /* std. mode operation */ >>>>>>>> + .timeout = 200, /* Slave response timeout(ms) */ >>>>>>>> + .sm = I2C_FREQ_MODE_FAST, >>>>>>> >>>>>>> How is this possible? you are setting clk_freq as 100kb/s and mode >>>>>>> as fast mode which is supposed to be 400kb/s. >>>>>> >>>>>> That's not how I read it: >>>>> >>>>> But it is not readable. It confuses people. >>>> >>>> I understood it. :) >>>> >>>> If you think it's unclear speak to the author, Linus. He's CC'ed. >>> >>> Author of what? The i2c driver was written by Srinidhi. (The >>> MODULE_AUTHOR() clause should be a good hint...) >> >> Actually, we appear to have our wires crossed. You wrote the board data >> stuff below, which changes the mode from STANDARD to FAST, no doubt >> using Srinidhi's struct explanation comments found in >> arch/arm/plat-nomadik/include/plat/i2c.h. >> >> > I'll cook a separate patch for this or something. >> >> Cool, thanks Linus. >> >> But you're correct in what you say Linus. Srinidhi, the comments which >> are you say are confusing are the bits you are the author of: >> e208c447bd728920e4f3d438a706344ea31249b9? > > yes, it is of course evident that it's my commit from git. > I think you are not catching my point. What I mean is: > fast mode devices are downward compatible and can communicate > with the devices with standard only mode. Those comments in that > enum says exactly that (with "up to" keyword). However the code > which configures the bus in fast mode and restrict the frequency > to operate in 100 kb/s without any reason, and this creates > confusion.. > > Perhaps, I think we need to remove one of these > parameters as configurable options and derive out the > frequency based on the mode of operation..
I think Linus is fixing the frequency issues in platform code and I have done so from Device Tree, so I think we're hot-to-trot.
Linus, Srinidhi,
If you're happy with the patch now (not withstanding the removal of slsu, which I'll do in a separate patch), can you ack it please? By the way, which tree will this go through?
-- Lee Jones Linaro ST-Ericsson Landing Team Lead M: +44 77 88 633 515 Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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