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([2600:1700:e321:62f0:da43:aeff:fecc:bfd5]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-22db5221c60sm11668675ad.228.2025.04.24.05.21.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 24 Apr 2025 05:21:41 -0700 (PDT) Sender: Guenter Roeck Message-ID: Date: Thu, 24 Apr 2025 05:21:40 -0700 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 2/2] i2c: i801: don't instantiate spd5118 if SPD Write Disable is set To: "Yo-Jung (Leo) Lin" , Jean Delvare , Andi Shyti , Wolfram Sang Cc: "Chia-Lin Kao (AceLan)" , linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org References: <20250424-for-upstream-i801-spd5118-no-instantiate-v1-0-627398268a1f@canonical.com> <20250424-for-upstream-i801-spd5118-no-instantiate-v1-2-627398268a1f@canonical.com> Content-Language: en-US From: Guenter Roeck Autocrypt: addr=linux@roeck-us.net; keydata= xsFNBE6H1WcBEACu6jIcw5kZ5dGeJ7E7B2uweQR/4FGxH10/H1O1+ApmcQ9i87XdZQiB9cpN RYHA7RCEK2dh6dDccykQk3bC90xXMPg+O3R+C/SkwcnUak1UZaeK/SwQbq/t0tkMzYDRxfJ7 nyFiKxUehbNF3r9qlJgPqONwX5vJy4/GvDHdddSCxV41P/ejsZ8PykxyJs98UWhF54tGRWFl 7i1xvaDB9lN5WTLRKSO7wICuLiSz5WZHXMkyF4d+/O5ll7yz/o/JxK5vO/sduYDIlFTvBZDh gzaEtNf5tQjsjG4io8E0Yq0ViobLkS2RTNZT8ICq/Jmvl0SpbHRvYwa2DhNsK0YjHFQBB0FX IdhdUEzNefcNcYvqigJpdICoP2e4yJSyflHFO4dr0OrdnGLe1Zi/8Xo/2+M1dSSEt196rXaC kwu2KgIgmkRBb3cp2vIBBIIowU8W3qC1+w+RdMUrZxKGWJ3juwcgveJlzMpMZNyM1jobSXZ0 VHGMNJ3MwXlrEFPXaYJgibcg6brM6wGfX/LBvc/haWw4yO24lT5eitm4UBdIy9pKkKmHHh7s jfZJkB5fWKVdoCv/omy6UyH6ykLOPFugl+hVL2Prf8xrXuZe1CMS7ID9Lc8FaL1ROIN/W8Vk BIsJMaWOhks//7d92Uf3EArDlDShwR2+D+AMon8NULuLBHiEUQARAQABzTJHdWVudGVyIFJv ZWNrIChMaW51eCBhY2NvdW50KSA8bGludXhAcm9lY2stdXMubmV0PsLBgQQTAQIAKwIbAwYL CQgHAwIGFQgCCQoLBBYCAwECHgECF4ACGQEFAlVcphcFCRmg06EACgkQyx8mb86fmYFg0RAA nzXJzuPkLJaOmSIzPAqqnutACchT/meCOgMEpS5oLf6xn5ySZkl23OxuhpMZTVX+49c9pvBx hpvl5bCWFu5qC1jC2eWRYU+aZZE4sxMaAGeWenQJsiG9lP8wkfCJP3ockNu0ZXXAXwIbY1O1 c+l11zQkZw89zNgWgKobKzrDMBFOYtAh0pAInZ9TSn7oA4Ctejouo5wUugmk8MrDtUVXmEA9 7f9fgKYSwl/H7dfKKsS1bDOpyJlqhEAH94BHJdK/b1tzwJCFAXFhMlmlbYEk8kWjcxQgDWMu GAthQzSuAyhqyZwFcOlMCNbAcTSQawSo3B9yM9mHJne5RrAbVz4TWLnEaX8gA5xK3uCNCeyI sqYuzA4OzcMwnnTASvzsGZoYHTFP3DQwf2nzxD6yBGCfwNGIYfS0i8YN8XcBgEcDFMWpOQhT Pu3HeztMnF3HXrc0t7e5rDW9zCh3k2PA6D2NV4fews9KDFhLlTfCVzf0PS1dRVVWM+4jVl6l HRIAgWp+2/f8dx5vPc4Ycp4IsZN0l1h9uT7qm1KTwz+sSl1zOqKD/BpfGNZfLRRxrXthvvY8 BltcuZ4+PGFTcRkMytUbMDFMF9Cjd2W9dXD35PEtvj8wnEyzIos8bbgtLrGTv/SYhmPpahJA l8hPhYvmAvpOmusUUyB30StsHIU2LLccUPPOwU0ETofVZwEQALlLbQeBDTDbwQYrj0gbx3bq 7kpKABxN2MqeuqGr02DpS9883d/t7ontxasXoEz2GTioevvRmllJlPQERVxM8gQoNg22twF7 pB/zsrIjxkE9heE4wYfN1AyzT+AxgYN6f8hVQ7Nrc9XgZZe+8IkuW/Nf64KzNJXnSH4u6nJM J2+Dt274YoFcXR1nG76Q259mKwzbCukKbd6piL+VsT/qBrLhZe9Ivbjq5WMdkQKnP7gYKCAi pNVJC4enWfivZsYupMd9qn7Uv/oCZDYoBTdMSBUblaLMwlcjnPpOYK5rfHvC4opxl+P/Vzyz 6WC2TLkPtKvYvXmdsI6rnEI4Uucg0Au/Ulg7aqqKhzGPIbVaL+U0Wk82nz6hz+WP2ggTrY1w ZlPlRt8WM9w6WfLf2j+PuGklj37m+KvaOEfLsF1v464dSpy1tQVHhhp8LFTxh/6RWkRIR2uF I4v3Xu/k5D0LhaZHpQ4C+xKsQxpTGuYh2tnRaRL14YMW1dlI3HfeB2gj7Yc8XdHh9vkpPyuT nY/ZsFbnvBtiw7GchKKri2gDhRb2QNNDyBnQn5mRFw7CyuFclAksOdV/sdpQnYlYcRQWOUGY HhQ5eqTRZjm9z+qQe/T0HQpmiPTqQcIaG/edgKVTUjITfA7AJMKLQHgp04Vylb+G6jocnQQX JqvvP09whbqrABEBAAHCwWUEGAECAA8CGwwFAlVcpi8FCRmg08MACgkQyx8mb86fmYHNRQ/+ J0OZsBYP4leJvQF8lx9zif+v4ZY/6C9tTcUv/KNAE5leyrD4IKbnV4PnbrVhjq861it/zRQW cFpWQszZyWRwNPWUUz7ejmm9lAwPbr8xWT4qMSA43VKQ7ZCeTQJ4TC8kjqtcbw41SjkjrcTG wF52zFO4bOWyovVAPncvV9eGA/vtnd3xEZXQiSt91kBSqK28yjxAqK/c3G6i7IX2rg6pzgqh hiH3/1qM2M/LSuqAv0Rwrt/k+pZXE+B4Ud42hwmMr0TfhNxG+X7YKvjKC+SjPjqp0CaztQ0H nsDLSLElVROxCd9m8CAUuHplgmR3seYCOrT4jriMFBtKNPtj2EE4DNV4s7k0Zy+6iRQ8G8ng QjsSqYJx8iAR8JRB7Gm2rQOMv8lSRdjva++GT0VLXtHULdlzg8VjDnFZ3lfz5PWEOeIMk7Rj trjv82EZtrhLuLjHRCaG50OOm0hwPSk1J64R8O3HjSLdertmw7eyAYOo4RuWJguYMg5DRnBk WkRwrSuCn7UG+qVWZeKEsFKFOkynOs3pVbcbq1pxbhk3TRWCGRU5JolI4ohy/7JV1TVbjiDI HP/aVnm6NC8of26P40Pg8EdAhajZnHHjA7FrJXsy3cyIGqvg9os4rNkUWmrCfLLsZDHD8FnU mDW4+i+XlNFUPUYMrIKi9joBhu18ssf5i5Q= In-Reply-To: <20250424-for-upstream-i801-spd5118-no-instantiate-v1-2-627398268a1f@canonical.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 4/23/25 20:35, Yo-Jung (Leo) Lin wrote: > If SPD Write Disable bit in the SMBus is enabled, writing data to > addresses from 0x50 to 0x57 is forbidden. This may lead to the > following issues for spd5118 device: > > 1) Writes to the sensor hwmon sysfs attributes will always result > in ENXIO. > > 2) System-wide resume, errors may occur during regcache sync, > resulting in the following error messages: > > kernel: spd5118 1-0050: Failed to write b = 0: -6 > kernel: spd5118 1-0050: PM: dpm_run_callback(): spd5118_resume [spd5118] returns -6 > kernel: spd5118 1-0050: PM: failed to resume async: error -6 > > 3) nvmem won't be usable, because writing to the page selector becomes > impossible. > > Also, spd5118 from some manufacturers may set the page to a value != 0 It is the BIOS vendor, not the spd5118 chip vendor. > after a sensor reset. This will make the sensor not functional unless board reset > its MR11 register can be changed, which is impossible due to writes being > disabled. > > To address these issues, don't instantiate it at all if SPD Write Disable > bit is set. > > Signed-off-by: Yo-Jung (Leo) Lin > --- > drivers/i2c/i2c-smbus.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/drivers/i2c/i2c-smbus.c b/drivers/i2c/i2c-smbus.c > index 97e833895dd7..cb7ef6a7a174 100644 > --- a/drivers/i2c/i2c-smbus.c > +++ b/drivers/i2c/i2c-smbus.c > @@ -378,6 +378,7 @@ void i2c_register_spd(struct i2c_adapter *adap, bool write_disabled) > u16 handle; > u8 common_mem_type = 0x0, mem_type; > u64 mem_size; > + bool scan_needed = true; I'd suggest to name the variable "instantiate", but that is really a nitpick. Reviewed-by: Guenter Roeck > const char *name; > > while ((handle = dmi_memdev_handle(slot_count)) != 0xffff) { > @@ -438,6 +439,7 @@ void i2c_register_spd(struct i2c_adapter *adap, bool write_disabled) > case 0x22: /* DDR5 */ > case 0x23: /* LPDDR5 */ > name = "spd5118"; > + scan_needed = !write_disabled; > break; > default: > dev_info(&adap->dev, > @@ -461,6 +463,9 @@ void i2c_register_spd(struct i2c_adapter *adap, bool write_disabled) > addr_list[0] = 0x50 + n; > addr_list[1] = I2C_CLIENT_END; > > + if (!scan_needed) > + continue; > + > if (!IS_ERR(i2c_new_scanned_device(adap, &info, addr_list, NULL))) { > dev_info(&adap->dev, > "Successfully instantiated SPD at 0x%hx\n", >