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Message-ID: <1490867763.708.62.camel@linux.intel.com>
Subject: Re: [PATCH] serial: Do not treat the IIR register as a bitfield
From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Olliver Schinagl <oliver@schinagl.nl>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jslaby@suse.com>, Laxman Dewangan <ldewangan@nvidia.com>,
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        Alexandre Courbot <gnurou@gmail.com>,
        "David S . Miller" <davem@davemloft.net>
Cc: dev@linux-sunxi.org, Ed Blake <ed.blake@imgtec.com>,
        Alexander Sverdlin <alexander.sverdlin@nokia.com>,
        Yegor Yefremov <yegorslists@googlemail.com>,
        Wan Ahmad Zainie <wan.ahmad.zainie.wan.mohamad@intel.com>,
        Kefeng Wang <wangkefeng.wang@huawei.com>,
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        David Lechner <david@lechnology.com>,
        Jan Kiszka <jan.kiszka@siemens.com>, linux-serial@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-tegra@vger.kernel.org,
        sparclinux@vger.kernel.org
Date: Thu, 30 Mar 2017 12:56:03 +0300
In-Reply-To: <20170329184431.6226-1-oliver@schinagl.nl>
References: <20170329184431.6226-1-oliver@schinagl.nl>
Organization: Intel Finland Oy
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On Wed, 2017-03-29 at 20:44 +0200, Olliver Schinagl wrote:
> It seems that at some point, someone made the assumption that the UART
> Interrupt ID Register was a bitfield and started to check if certain
> bits where set.
> 
> Actually however the register contains interrupt ID's where only the
> MSB
> seems to be used singular and the rest share at least one bit. Thus
> doing bitfield operations is wrong.
> 
> This patch cleans up the serial_reg include file by ordering it and
> replacing the UART_IIR_ID 'mask' with a proper mask for the register.
> The OMAP uart appears to have used the two commonly 'reserved' bits 4
> and 5 and thus get an UART_IIR_EXT_MASK for these two bits.
> 
> This patch then goes over all UART_IIR_* users and changes the code
> from
> bitfield checking, to ID checking instead.


Looking to implementation I would rather go with some helper like

int serial_in_IIR(port, [additional mask])
{
 return port->serial_in(port, UART_IIR) & (_IIR_MASK [| additional
mask]);
}

-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy