From mboxrd@z Thu Jan 1 00:00:00 1970 From: tony@atomide.com (Tony Lindgren) Date: Fri, 15 Apr 2016 08:22:16 -0700 Subject: [PATCH v2] pinctrl: pinctrl-single: Fix pcs_parse_bits_in_pinctrl_entry to use __ffs than ffs In-Reply-To: References: <1460609956-26539-1-git-send-email-j-keerthy@ti.com> Message-ID: <20160415152215.GR5995@atomide.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org * Linus Walleij [160415 02:29]: > On Thu, Apr 14, 2016 at 6:59 AM, Keerthy wrote: > > > pcs_parse_bits_in_pinctrl_entry uses ffs which gives bit indices > > ranging from 1 to MAX. This leads to a corner case where we try to request > > the pin number = MAX and fails. > > > > bit_pos value is being calculted using ffs. pin_num_from_lsb uses > > bit_pos value. pins array is populated with: > > > > pin + pin_num_from_lsb. > > > > The above is 1 more than usual bit indices as bit_pos uses ffs to compute > > first set bit. Hence the last of the pins array is populated with the MAX > > value and not MAX - 1 which causes error when we call pin_request. > > > > mask_pos is rightly calculated as ((pcs->fmask) << (bit_pos - 1)) > > Consequently val_pos and submask are correct. > > > > Hence use __ffs which gives (ffs(x) - 1) as the first bit set. > > > > fixes: 4e7e8017a8 ("pinctrl: pinctrl-single: enhance to configure multiple pins of different modules") > > Signed-off-by: Keerthy > > --- > > > > Changes in v2: > > > > * Changed pcs->fshift to use __ffs instead of ffs to be consistent. > > > > Boot tesed on da850-evm and checked the pinctrl sysfs nodes. > > Patch applied for fixes with Tony's ACK. > > Should it also be tagged for stable? Probably a good idea, I can see somebody pulling hair out because of this in various product trees. Regards, Tony