Messages in this thread | | | Subject | Re: [PATCH] i2c: designware: do not disable adapter after transfer | From | Lucas De Marchi <> | Date | Mon, 25 Apr 2016 12:04:47 -0300 |
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On 04/25/2016 08:51 AM, Jarkko Nikula wrote:
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>> @@ -413,8 +416,16 @@ static void i2c_dw_xfer_init(struct dw_i2c_dev *dev) >> struct i2c_msg *msgs = dev->msgs; >> u32 ic_con, ic_tar = 0; >> >> - /* Disable the adapter */ >> - __i2c_dw_enable(dev, false); >> + if (dev->enabled) { >> + u32 ic_status; >> + >> + /* check ic_tar and ic_con can be dynamically updated */ >> + ic_status = dw_readl(dev, DW_IC_STATUS); >> + if (ic_status & DW_IC_STATUS_ACTIVITY >> + || !(ic_status & DW_IC_STATUS_TX_EMPTY)) { >> + __i2c_dw_enable(dev, false); >> + } >> + } >> > Worth to double check this. I see bit 1 means TX FIFO not full and bit 2 > is TX FIFO completely empty.
the conditions to be able to update IC_TAR dynamically are:
- Adapter isn't doing any TX/RX operation (IC_STATUS[5] == 0) and - There are no entries in TX FIFO (IC_STATUS[2] == 1)
So... yeah, the condition above seems wrong. I should be reading bit 5, not bit 1. Thanks! However:
IC_STATUS[5] signals activity for master mode IC_STATUS[6] signals activity for slave mode IC_STATUS[0] is IC_STATUS[5]|IC_STATUS[6]
And this controller is never in slave mode, only master mode, so it should be equivalent.
I wonder if I even have to check bit 5 since AFAICS we wouldn't be able to even call this function if there were any operation on tx/rx.
> > Otherwise I'm fine with the patch as long as it works for Christian. >
Anyway, I'll re-test with bit 5 checked and send an update.
Lucas De Marchi
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