Re: [PATCH] spi: bcm2835aux: use 64-bit arithmetic instead of 32-bit

From: Eric Anholt
Date: Thu Feb 08 2018 - 03:24:22 EST


"Gustavo A. R. Silva" <gustavo@xxxxxxxxxxxxxx> writes:

> Add suffix ULL to constant 9 in order to give the compiler complete
> information about the proper arithmetic to use. Notice that this
> constant is used in a context that expects an expression of type
> unsigned long long (64 bits, unsigned).
>
> The expression tfr->len * 9 * 1000000 is currently being evaluated
> using 32-bit arithmetic.
>
> Addresses-Coverity-ID: 1339619
> Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>

The effect looks like it would be that we would have chosen polling mode
instead of waiting for interrupts for some transfers >477 seconds.
Seems like a good fix for an unlikely bug.

Reviewed-by: Eric Anholt <eric@xxxxxxxxxx>

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