From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bartosz Golaszewski Subject: Re: [PATCH v2 2/2] gpio: Add Cadence GPIO driver Date: Tue, 18 Dec 2018 13:50:48 +0100 Message-ID: References: <20181217153652.20056-1-jank@cadence.com> <20181217153652.20056-3-jank@cadence.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Linus Walleij Cc: Jan Kotas , Rob Herring , Mark Rutland , linux-gpio , linux-devicetree , LKML List-Id: linux-gpio@vger.kernel.org pon., 17 gru 2018 o 23:22 Linus Walleij napisa= =C5=82(a): > > On Mon, Dec 17, 2018 at 4:51 PM Bartosz Golaszewski > wrote: > > > The driver looks good but is there any particular reason not to use > > regmap for register IO? > > I thought we only use regmap for MMIO when the register range is > shared (as in a system controller) so that some registers are for this, > some register or even bits in a register for some other driver, so they > need the spinlock in the regmap to protect the register range. > This is what syscon is for. Regmap simply abstracts any register IO. For instance: there's no locking in this driver. Are we sure it's not needed? Regmap provides internal locking for you in the form of a mutex or spinlock. Also: it looks like the interrupts here are quite simple with a single bit per interrupt in the status register and the same layout in the mask register - it could probably profit from using the regmap_irq_chip and not bother with reimplementing irq_chip callbacks. > It is also nice for shadowing/caching of register contents I guess, > wat does this driver get from regmap MMIO? > Code shrinkage IMO. Note that I'm not blocking this from being merged - I just think that using modern frameworks is always a good idea. Best regards, Bartosz Golaszewski > Yours, > Linus Walleij