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SubjectRe: [PATCH v4 3/5] i2c:ocores: add polling interface
On Mon, Feb 11, 2019 at 09:31:20AM +0100, Federico Vaga wrote:
> This driver assumes that an interrupt line is always available for
> the I2C master. This is not always the case and this patch adds support
> for a polling version.
> Report from Andrew Lunn:
> I did some timing tests for this. On my box, we request a udelay of
> 80uS. The kernel actually delays for about 79uS. We then spin in
> ocores_wait() for an additional 10-11uS, which is 3 to 4 iterations.
> There are actually 9 bits on the wire, not 8, since there is an
> ACK/NACK bit after the actual data transfer. So i changed the delay to
> (9 * 1000) / i2c->bus_clock_khz. That resulted in ocores_wait() mostly
> not looping at all. But for reading an 4K AT24 EEPROM, it increased
> the read time by 10ms, from 424ms to 434ms. So we should probably keep
> with 8.
> Signed-off-by: Federico Vaga <>
> Tested-by: Andrew Lunn <>

Fixed these checkpatch warnings:

WARNING: 'transfered' may be misspelled - perhaps 'transferred'?
#111: FILE: drivers/i2c/busses/i2c-ocores.c:306:
+ * We wait for the data to be transfered (8bit),

CHECK: Please don't use multiple blank lines
#129: FILE: drivers/i2c/busses/i2c-ocores.c:324:

WARNING: 'transfered' may be misspelled - perhaps 'transferred'?
#154: FILE: drivers/i2c/busses/i2c-ocores.c:349:
+ break; /* all messages have been transfered */

and applied to for-next, thanks!

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