You are
right, moving the event clearing statement is much easier and cleaner.
Let the interrupt be the loop.
Thanks Dan !
Dan Malek wrote:
On May 19, 2005, at 3:34 PM, Guillaume Autran wrote:
Is it better like this ?
Yes, but now I see one problem with it. :-)
We have to clear all events even though we may not
handle all of them. Your while loop filters only the events
we process, but there could be others causing the interrupt
which will never get cleared. In this case we end up with
an infinite interrupt loop where we don't process anything,
but we don't make the interrupt go away, either. It may be
easier to forget the loop, just read/clear the event register
up front, then process based on the events based upon
what we found. It's what we tend to do in the other drivers.
The functions called to do the rx/tx processing have loops
in them to process all of the data they find, so it isn't likely
you have left anything behind. If you want to try to save
the interrupt overhead, change it to do/while, check again
at the end before the exit.
Thanks.
-- Dan
diff -Nru linux-2.6.12-rc4.org/drivers/serial/cpm_uart/cpm_uart_core.c linux-2.6.12-rc4.new/drivers/serial/cpm_uart/cpm_uart_core.c
--- linux-2.6.12-rc4.org/drivers/serial/cpm_uart/cpm_uart_core.c 2005-05-07 01:20:31.000000000 -0400
+++ linux-2.6.12-rc4.new/drivers/serial/cpm_uart/cpm_uart_core.c 2005-05-19 16:23:13.000000000 -0400
@@ -336,22 +336,22 @@
if (IS_SMC(pinfo)) {
events = smcp->smc_smce;
+ smcp->smc_smce = events;
if (events & SMCM_BRKE)
uart_handle_break(port);
if (events & SMCM_RX)
cpm_uart_int_rx(port, regs);
if (events & SMCM_TX)
cpm_uart_int_tx(port, regs);
- smcp->smc_smce = events;
} else {
events = sccp->scc_scce;
+ sccp->scc_scce = events;
if (events & UART_SCCM_BRKE)
uart_handle_break(port);
if (events & UART_SCCM_RX)
cpm_uart_int_rx(port, regs);
if (events & UART_SCCM_TX)
cpm_uart_int_tx(port, regs);
- sccp->scc_scce = events;
}
return (events) ? IRQ_HANDLED : IRQ_NONE;
}
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