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Fri, 01 May 2026 07:32:21 -0700 (PDT) Message-ID: <2b3b7c42-95ed-4195-83ac-63e6fe171e6c@gmail.com> Date: Fri, 1 May 2026 20:02:15 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 1/3] hwmon: (ads7871) Fix endianness bug in 16-bit register reads To: David Laight Cc: Guenter Roeck , linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org, shuah@kernel.org, me@brighamcampbell.com, Sashiko References: <20260501023530.31160-1-tabreztalks@gmail.com> <20260501023530.31160-2-tabreztalks@gmail.com> <20260501094902.05ce6d37@pumpkin> Content-Language: en-US From: Tabrez Ahmed In-Reply-To: <20260501094902.05ce6d37@pumpkin> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 5/1/26 14:19, David Laight wrote: > Isn't it enough to just byteswap the result? so: > return le16toh(ret); > The whole thing can be: > return le16toh(spi_w8r16(spi, reg | INST_READ_BM | INST_16BIT_BM)); > (although I suspect sparse bleats and needs an annoying (__force __le16) cast) Hi David, Good point, spi_w8r16() is definitely cleaner and cuts out the buffer allocations entirely. I tried the one-liner approach, but le16toh caused a build error because it's not available in the kernel headers. I will swap it for le16_to_cpu in the final patch. I'm going to split the implementation slightly in v6 to catch negative error codes before the conversion and to match the bitwise assignment style used in the rest of this driver: static int ads7871_read_reg16(struct spi_device *spi, int reg) { int ret; reg = reg | INST_READ_BM | INST_16BIT_BM; ret = spi_w8r16(spi, reg); if (ret < 0) return ret; return le16_to_cpu((__force __le16)ret); } Guenter this also pulls in your suggestion to combine the bitwise flags. I'll get v6 out shortly. Thanks, Tabrez