net: mvpp2: handle too large value in mvpp2_rx_time_coal_set()

When configuring the MVPP2_ISR_RX_THRESHOLD_REG with the RX coalescing
time threshold, we do not check for the maximum allowed value supported
by the driver, which means we might overflow and use a bogus value. This
commit adds a check for this situation, and if a value higher than what
is supported by the hardware is provided, then we use the maximum value
supported by the hardware.

In order to achieve this in a way that avoids overflow and rounding
errors, we introduce two utility functions mvpp2_usec_to_cycles() and
cycles_to_usec(). Many thanks to Russell King for suggesting this
implementation.

Signed-off-by: Thomas Petazzoni <[email protected]>
Acked-by: Russell King <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

0 files changed, 0 insertions, 0 deletions