Messages in this thread | | | Date | Wed, 28 May 2014 12:03:15 +0200 | Subject | Re: [PATCH v3 10/13] mmc: mmci: add Qcom specifics of clk and datactrl registers. | From | Ulf Hansson <> |
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On 28 May 2014 11:41, Srinivas Kandagatla <srinivas.kandagatla@linaro.org> wrote: > Hi Ulf, > > > On 26/05/14 22:38, Srinivas Kandagatla wrote: >>>> >>>> 2 files changed, 28 insertions(+) >>>> >>>> diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c >>>> index 17e7f6a..6434f5b1 100644 >>>> --- a/drivers/mmc/host/mmci.c >>>> +++ b/drivers/mmc/host/mmci.c >>>> @@ -185,6 +185,10 @@ static struct variant_data variant_qcom = { >>>> .fifosize = 16 * 4, >>>> .fifohalfsize = 8 * 4, >>>> .clkreg = MCI_CLK_ENABLE, >>>> + .clkreg_enable = MCI_QCOM_CLK_FLOWENA | >>>> + MCI_QCOM_CLK_FEEDBACK_CLK, >>> >>> >>> Obviously I don't have the in-depth knowledge about the Qcom variant, >>> but comparing the ST variant here made me think. >>> >>> Using the feeback clock internal logic in the ST variant, requires the >>> corresponding feedback clock pin signal on the board, to be >>> routed/connected. Typically we used this for SD cards, which involved >>> using an external level shifter circuit. >>> >>> Is it correct to enable this bit for all cases, including eMMC? >>> >> You are correct, FBCLK should specific to the board, and I will try to >> do something on the same lines as ST variant in next version. > > I get lot of I/O errors when I remove this flag for test.
Running eMMC I suppose?
> > I rechecked schematics and datasheet, the feedback clk that we refer here is > the the feedback clk from CLK pad, there is no separate input pad for fbclk. > So I think this is internally feedbacked clk. > > This selection is configuring bits to latch data and command coming in using > feedback clock from CLK pad.
Seems like it's strange to have this bit configurable then. I guess it would be hard to tell under what circumstances you don't want this bit set.
Anyway, it's not a big deal to me - let's keep it as is for now.
Kind regards Ulf Hansson
> > I will make sure that the macro is named more appropriately to reflect the > same. > > thanks, > srini
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