Alexey Brodkin 0a764db103 stmmac: Discard masked flags in interrupt status register
DW GMAC databook says the following about bits in "Register 15 (Interrupt
Mask Register)":
--------------------------->8-------------------------
When set, this bit __disables_the_assertion_of_the_interrupt_signal__
because of the setting of XXX bit in Register 14 (Interrupt
Status Register).
--------------------------->8-------------------------

In fact even if we mask one bit in the mask register it doesn't prevent
corresponding bit to appear in the status register, it only disables
interrupt generation for corresponding event.

But currently we expect a bit different behavior: status bits to be in
sync with their masks, i.e. if mask for bit A is set in the mask
register then bit A won't appear in the interrupt status register.

This was proven to be incorrect assumption, see discussion here [1].
That misunderstanding causes unexpected behaviour of the GMAC, for
example we were happy enough to just see bogus messages about link
state changes.

So from now on we'll be only checking bits that really may trigger an
interrupt.

[1] https://lkml.org/lkml/2016/11/3/413

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Cc: Fabrice Gasnier <fabrice.gasnier@st.com>
Cc: Joachim Eastwood <manabian@gmail.com>
Cc: Phil Reid <preid@electromag.com.au>
Cc: David Miller <davem@davemloft.net>
Cc: Alexandre Torgue <alexandre.torgue@gmail.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-29 18:15:18 -05:00
2017-01-18 15:14:15 -07:00
2017-01-27 12:44:32 -08:00
2017-01-11 19:49:27 +01:00
2017-01-17 15:04:59 +01:00
2017-01-22 12:54:15 -08:00

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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