Messages in this thread | ![/](/images/icornerl.gif) | | Subject | Re: [PATCH] i2c: designware: do not disable adapter after transfer | From | Jarkko Nikula <> | Date | Wed, 27 Apr 2016 10:47:11 +0300 |
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On 04/25/2016 06:04 PM, Lucas De Marchi wrote: > > > On 04/25/2016 08:51 AM, Jarkko Nikula wrote: > > [ ... ] > >>> @@ -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: > It reads above, bit 2 instead of 1 for TX FIFO checking and then either bit 5 or 0 for activity checking.
I'd say it's probably better to check bit 5 instead of bit 0 even bit 0 is or'ed from bits 5 and 6. I don't know how possible slave support and slave being active will play here so it's best to follow spec.
-- jarkko
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