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Thu, 14 Mar 2019 10:44:09 -0700 (PDT) Date: Thu, 14 Mar 2019 10:44:08 -0700 From: Guenter Roeck To: John Garry Cc: jdelvare@suse.com, bhelgaas@google.com, rafael@kernel.org, arnd@arndb.de, lorenzo.pieralisi@arm.com, bp@suse.de, linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, wangkefeng.wang@huawei.com, linuxarm@huawei.com Subject: Re: [RFC PATCH 2/2] hwmon: (f71805f): Use request_region() in f71805f_init() Message-ID: <20190314174408.GD14159@roeck-us.net> References: <1552582516-70855-1-git-send-email-john.garry@huawei.com> <1552582516-70855-3-git-send-email-john.garry@huawei.com> <20190314170534.GB14159@roeck-us.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 14, 2019 at 05:21:32PM +0000, John Garry wrote: > On 14/03/2019 17:05, Guenter Roeck wrote: > >On Fri, Mar 15, 2019 at 12:55:16AM +0800, John Garry wrote: > >>Currently the driver does not call request_region() prior to > >>accessing IO port regions in f71805f_init(), so add it. > >> > >>Signed-off-by: John Garry > >>--- > >> drivers/hwmon/f71805f.c | 13 ++++++++++++- > >> 1 file changed, 12 insertions(+), 1 deletion(-) > >> > >>diff --git a/drivers/hwmon/f71805f.c b/drivers/hwmon/f71805f.c > >>index 73c681162653..910082c7f184 100644 > >>--- a/drivers/hwmon/f71805f.c > >>+++ b/drivers/hwmon/f71805f.c > >>@@ -1617,10 +1617,21 @@ static int __init f71805f_init(void) > >> int err; > >> unsigned short address; > >> struct f71805f_sio_data sio_data; > >>+ struct resource *res; > >>+ size_t size = 0x4e - 0x2e + SIO_REG_ADDR + 4; > >>+ > >>+ /* Request the whole 0x2e - 0x4e region */ > >>+ res = request_region(0x2e, size, "f71805f"); > > > > Hi Guenter, > > >request_muxed_region() would be a better choice here since it doesn't > >bail out immediately if the region is temporarily busy. > > Are you saying that this region could be busy due to another driver > accessing this same region (probably for the same purpose)? > Depends on the definition of "same reason". To access the chip's Super-IO configuration registers, yes, that can happen. I don't see it used in the kernel today, but examples would be someone adding support for the chips supported by this driver to gpio-f7188x, or adding support for the F71872 watchdog to the f71808e_wdt driver. Guenter