On 4/1/2022 1:19 AM, Dmitry Osipenko wrote:
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On 3/30/22 14:22, Ashish Mhetre wrote:
...
If we are to remove this callback then how to handle unknown interrupt
channel error?
Create a common helper function that returns ID of the raised channel or
errorno if not bits are set.
So something like this:
int status_to_channel(const struct tegra_mc *mc, u32 status,
unsigned int *mc_channel)
{
if ((status & mc->soc->ch_intmask) == 0)
return -EINVAL;
*mc_channel = __ffs((status & mc->soc->ch_intmask) >>
mc->soc->status_reg_chan_shift);
return 0;
}
Correct?
Yes
Also we want to handle interrupts on one channel at a time and then
clear it from status register. There can be interrupts on multiple
channel. So multiple bits from status will be set. Hence it will be
hard to parameterize shift such that it gives appropriate channel.
So I think current approach is fine. Please correct me if I am wrong
somewhere.
You may do the following:
1. find the first channel bit set in the status reg
2. handle that channel
3. clear only the handled status bit, don't clear the other bits
4. return from interrupt
If there are other bits set, then interrupt handler will fire again and
next channel will be handled.
For clearing status bit after handling, we can retrieve channel bit by
something like this:
ch_bit = BIT(*mc_channel) << mc->soc->status_reg_chan_shift;
Correct?
Yes
Perhaps using FIELD_PREP() and alike helpers could make it look nice in
the code.
I tried using FIELD_PREP() and FIELD_GET() for our use-case but
compilation is failing because these macros require the mask to be
compile time constant and our mask "mc->soc->ch_intmask" cannot qualify
to be compile time constant.
