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[216.228.125.128]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-aee7de19d3fsm1745501a12.18.2025.02.27.09.37.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 27 Feb 2025 09:37:05 -0800 (PST) Date: Thu, 27 Feb 2025 12:37:02 -0500 From: Yury Norov To: Jiri Slaby Cc: Kuan-Wei Chiu , tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, jk@ozlabs.org, joel@jms.id.au, eajames@linux.ibm.com, andrzej.hajda@intel.com, neil.armstrong@linaro.org, rfoss@kernel.org, maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de, airlied@gmail.com, simona@ffwll.ch, dmitry.torokhov@gmail.com, mchehab@kernel.org, awalls@md.metrocast.net, hverkuil@xs4all.nl, miquel.raynal@bootlin.com, richard@nod.at, vigneshr@ti.com, louis.peens@corigine.com, andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, pabeni@redhat.com, parthiban.veerasooran@microchip.com, arend.vanspriel@broadcom.com, johannes@sipsolutions.net, gregkh@linuxfoundation.org, akpm@linux-foundation.org, hpa@zytor.com, alistair@popple.id.au, linux@rasmusvillemoes.dk, Laurent.pinchart@ideasonboard.com, jonas@kwiboo.se, jernej.skrabec@gmail.com, kuba@kernel.org, linux-kernel@vger.kernel.org, linux-fsi@lists.ozlabs.org, dri-devel@lists.freedesktop.org, linux-input@vger.kernel.org, linux-media@vger.kernel.org, linux-mtd@lists.infradead.org, oss-drivers@corigine.com, netdev@vger.kernel.org, linux-wireless@vger.kernel.org, brcm80211@lists.linux.dev, brcm80211-dev-list.pdl@broadcom.com, linux-serial@vger.kernel.org, bpf@vger.kernel.org, jserv@ccns.ncku.edu.tw, Yu-Chun Lin Subject: Re: [PATCH 02/17] bitops: Add generic parity calculation for u64 Message-ID: References: <20250223164217.2139331-1-visitorckw@gmail.com> <20250223164217.2139331-3-visitorckw@gmail.com> Precedence: bulk X-Mailing-List: linux-input@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Thu, Feb 27, 2025 at 07:38:58AM +0100, Jiri Slaby wrote: > On 26. 02. 25, 19:33, Yury Norov wrote: > > > Not in cases where macros are inevitable. I mean, do we need parityXX() for > > > XX in (8, 16, 32, 64) at all? Isn't the parity() above enough for everybody? > > > > The existing codebase has something like: > > > > int ret; > > > > ret = i3c_master_get_free_addr(m, last_addr + 1); > > ret |= parity8(ret) ? 0 : BIT(7) > > > > So if we'll switch it to a macro like one above, it will become a > > 32-bit parity. It wouldn't be an error because i3c_master_get_free_addr() > > returns an u8 or -ENOMEM, and the error code is checked explicitly. > > > > But if we decide to go with parity() only, some users will have to > > call it like parity((u8)val) explicitly. Which is not bad actually. > > That cast looks ugly -- we apparently need parityXX(). (In this particular > case we could do parity8(last_addr), but I assume there are more cases like > this.) Thanks for looking up the case for this. This parity8() is used in just 2 drivers - i3c and hwmon/spd5118. The hwmon driver looks good. I3C, yeah, makes this implied typecast, which is nasty regardless. This is the new code, and I think if we all agree that generic parity() would be a better API, it's a good time to convert existing users now. Thanks, Yury