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[2001:1c00:c32:7800:5bfa:a036:83f0:f9ec]) by smtp.gmail.com with ESMTPSA id x5-20020a1709065ac500b00993664a9987sm647322ejs.103.2023.09.14.01.21.07 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 14 Sep 2023 01:21:07 -0700 (PDT) Message-ID: <05b9b252-653c-7cf7-9b96-59d9f662b81e@redhat.com> Date: Thu, 14 Sep 2023 10:21:06 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH v16 1/4] usb: Add support for Intel LJCA device Content-Language: en-US, nl To: "Wu, Wentong" , Oliver Neukum , "gregkh@linuxfoundation.org" Cc: "arnd@arndb.de" , "mka@chromium.org" , "lee@kernel.org" , "wsa@kernel.org" , "kfting@nuvoton.com" , "broonie@kernel.org" , "linus.walleij@linaro.org" , "maz@kernel.org" , "brgl@bgdev.pl" , "linux-usb@vger.kernel.org" , "linux-i2c@vger.kernel.org" , "linux-spi@vger.kernel.org" , "linux-gpio@vger.kernel.org" , "andriy.shevchenko@linux.intel.com" , "heikki.krogerus@linux.intel.com" , "andi.shyti@linux.intel.com" , "sakari.ailus@linux.intel.com" , "bartosz.golaszewski@linaro.org" , "Pandruvada, Srinivas" , "Wang, Zhifeng" References: <1694569212-10080-1-git-send-email-wentong.wu@intel.com> <1694569212-10080-2-git-send-email-wentong.wu@intel.com> From: Hans de Goede In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-gpio@vger.kernel.org Hi, On 9/14/23 03:05, Wu, Wentong wrote: >> From: Oliver Neukum >> >> On 13.09.23 03:40, Wentong Wu wrote: >> >>> +struct ljca_bank_descriptor { >>> + u8 bank_id; >>> + u8 pin_num; >>> + >>> + /* 1 bit for each gpio, 1 means valid */ >>> + u32 valid_pins; >> >> No endianness? > > On both sides, the endianness is same. Right, but normally USB drivers are also written so that they can work on big-endian CPUs. I realize that this driver will likely never be used with a big-endian CPU but still it is good practice to make the driver work on big-endian CPUs too. Even if it is just to set a good example when other drivers copy the code. So this should be: struct ljca_bank_descriptor { u8 bank_id; u8 pin_num; /* 1 bit for each gpio, 1 means valid */ __le32 valid_pins; } __packed; And then when reading valid_pins you should use: u32 valid_pins = get_unaligned_le32(&ljca_bank_descriptor.valid_pins); On x86_64 the compiler should optimize all of this away to just a regular read. Regards, Hans