On 6/14/19 6:02 AM, Dmitry Osipenko wrote:
14.06.2019 12:50, Bitan Biswas пишет:
On 6/13/19 5:28 AM, Dmitry Osipenko wrote:
13.06.2019 14:30, Bitan Biswas пишет:
On 6/12/19 7:30 AM, Dmitry Osipenko wrote:
11.06.2019 13:51, Bitan Biswas пишет:
Fix expression for residual bytes(less than word) transfer
in I2C PIO mode RX/TX.
Signed-off-by: Bitan Biswas <bbiswas@xxxxxxxxxx>
---
[snip]
/*
- * Update state before writing to FIFO. If this casues us
+ * Update state before writing to FIFO. If this causes us
* to finish writing all bytes (AKA buf_remaining goes to
0) we
* have a potential for an interrupt (PACKET_XFER_COMPLETE is
- * not maskable). We need to make sure that the isr sees
- * buf_remaining as 0 and doesn't call us back re-entrantly.
+ * not maskable).
*/
buf_remaining -= words_to_transfer * BYTES_PER_FIFO_WORD;
Looks like the comment could be removed altogether because it doesn't
make sense since interrupt handler is under xfer_lock which is kept
locked during of tegra_i2c_xfer_msg().
I would push a separate patch to remove this comment because of
xfer_lock in ISR now.
Moreover the comment says that "PACKET_XFER_COMPLETE is not maskable",
but then what I2C_INT_PACKET_XFER_COMPLETE masking does?
I2C_INT_PACKET_XFER_COMPLETE masking support available in Tegra chips
newer than Tegra30 allows one to not see interrupt after Packet transfer
complete. With the xfer_lock in ISR the scenario discussed in comment
can be ignored.
Also note that xfer_lock could be removed and replaced with a just
irq_enable/disable() calls in tegra_i2c_xfer_msg() because we only care
about IRQ not firing during of the preparation process.
This should need sufficient testing hence let us do it in a different series.
I don't think that there is much to test here since obviously it should work.
I shall push a patch for this as basic i2c read write test passed.
It also looks like tegra_i2c_[un]nmask_irq isn't really needed and all
IRQ's could be simply unmasked during the driver's probe, in that case
it may worth to add a kind of "in-progress" flag to catch erroneous
interrupts.
TX interrupt needs special handling if this change is done. Hence I think it should be
taken up after sufficient testing in a separate patch.
This one is indeed a bit more trickier. Probably another alternative could be to keep GIC
interrupt disabled while no transfer is performed, then you'll have to request interrupt
in a disabled state using IRQ_NOAUTOEN flag.
And yes, that all should be a separate changes if you're going to implement them.
OK
-Thanks,
Bitan
