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b=tj/fqrZsxjmWhzcZR/BTyM8O12qGISUKRfyL/L5i9en1HVJFcz21+4NmV6tKHIC0bpX0OzqgTlFB01aXRRGZ3p2UeynKkuOrjK5sQgh75Gc1o1tpydjRRiSFtP5mkBCKatJ0lTCoFQR2iusrkvEDNJbC7kdWvf1OLPJPYV0hfs4= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=amd.com; Received: from IA1PR12MB7736.namprd12.prod.outlook.com (2603:10b6:208:420::15) by BL4PR12MB9721.namprd12.prod.outlook.com (2603:10b6:208:4ed::12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.113.18; Mon, 15 Jun 2026 15:50:06 +0000 Received: from IA1PR12MB7736.namprd12.prod.outlook.com ([fe80::2274:9fed:8f3:8550]) by IA1PR12MB7736.namprd12.prod.outlook.com ([fe80::2274:9fed:8f3:8550%6]) with mapi id 15.21.0113.015; Mon, 15 Jun 2026 15:50:06 +0000 Message-ID: <1c00fb53-b72e-4d19-bc4e-4f68e6cd7305@amd.com> Date: Mon, 15 Jun 2026 16:50:03 +0100 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v7 5/5] iio: adc: versal-sysmon: add oversampling support To: Andy Shevchenko Cc: jic23@kernel.org, andy@kernel.org, dlechner@baylibre.com, nuno.sa@analog.com, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, conall.ogriofa@amd.com, michal.simek@amd.com, linux@roeck-us.net, erimsalih@gmail.com, linux-iio@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260614233722.2603459-1-salih.erim@amd.com> <20260614233722.2603459-6-salih.erim@amd.com> Content-Language: en-US From: "Erim, Salih" In-Reply-To: Content-Type: text/plain; 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On 15/06/2026 15:28, Andy Shevchenko wrote: > On Mon, Jun 15, 2026 at 12:37:22AM +0100, Salih Erim wrote: >> Add support for reading and writing the oversampling ratio through >> the IIO oversampling_ratio attribute. The hardware supports averaging >> 2, 4, 8, or 16 samples, plus a ratio of 1 (no averaging). >> >> Temperature and supply channels share oversampling configuration at >> the type level (all temperature channels share one ratio, all supply >> channels share another), exposed through info_mask_shared_by_type. >> >> The hardware encoding uses sample_count / 2 in a 4-bit field within >> the CONFIG register. Per-channel averaging enable registers must also >> be updated to activate or deactivate averaging. > > ... > >> +static int sysmon_osr_write_temp(struct sysmon *sysmon, int val) >> +{ >> + /* >> + * HW register encoding is sample_count / 2: >> + * 0=none, 1=2x, 2=4x, 4=8x, 8=16x (not log2-based). >> + */ >> + int hw_val = val >> 1; > > If, for some reason, val happens to be a small negative number, here might be > a surprising behaviour. The caller validates val against the oversampling_avail list {1, 2, 4, 8, 16} before calling, so negatives never reach here. But the parameter should be unsigned int to make that obvious. Will change in v8. > >> + unsigned int readback; >> + int ret; >> + >> + ret = regmap_update_bits(sysmon->regmap, SYSMON_CONFIG, >> + SYSMON_CONFIG_TEMP_SAT_OSR, >> + FIELD_PREP(SYSMON_CONFIG_TEMP_SAT_OSR, hw_val)); >> + if (ret) >> + return ret; >> + >> + /* >> + * Readback fence: the SysMon CONFIG register resides in the >> + * PMC domain behind the NoC. A posted write may not reach the >> + * hardware before the next MMIO access. Reading the register >> + * back forces the interconnect to complete the write, preventing >> + * a bus hang on the subsequent access. >> + */ >> + regmap_read(sysmon->regmap, SYSMON_CONFIG, &readback); >> + >> + return sysmon_set_avg_enable(sysmon, SYSMON_TEMP_EN_AVG_BASE, >> + SYSMON_TEMP_EN_AVG_COUNT, >> + hw_val ? ~0U : 0); > > Is the last parameter > 32-bit? If not, drop 'U' as it might have a nice > side-effect in case this become actually > 32-bit. Same for other cases. > In other words, using ~0U should be quite cautious. Will change to ~0. Same for both call sites. Thanks, Salih > >> +} > > -- > With Best Regards, > Andy Shevchenko > >