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([2a01:e0a:5ee:79d0:cf9d:bb30:5951:692]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-39eaf43cb43sm2138998f8f.65.2025.04.11.07.20.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 11 Apr 2025 07:20:12 -0700 (PDT) Message-ID: <8ea16b0a-85aa-4ff7-8531-9eb253a9575a@baylibre.com> Date: Fri, 11 Apr 2025 16:20:11 +0200 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 v2 2/2] rtc: mt6397: Fix mt6357 RTC year offset handling for hwclock commands To: AngeloGioacchino Del Regno , Eddie Huang , Sean Wang , Alexandre Belloni , Matthias Brugger , Macpaul Lin Cc: linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-rtc@vger.kernel.org, linux-kernel@vger.kernel.org References: <20250109-enable-rtc-v2-0-d7ddc3e73c57@baylibre.com> <20250109-enable-rtc-v2-2-d7ddc3e73c57@baylibre.com> <4d916221-d9ea-4e08-8d22-1be1982323ee@collabora.com> Content-Language: en-US From: Alexandre Mergnat In-Reply-To: <4d916221-d9ea-4e08-8d22-1be1982323ee@collabora.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 02/04/2025 15:03, AngeloGioacchino Del Regno wrote: > Il 02/04/25 12:51, Alexandre Mergnat ha scritto: >> The mt6357 RTC was failing when using the `hwclock -r --verbose` command, >> despite reading correctly through sysfs. There is high chance for other >> platform to be impacted by the year offset handling issue. >> >> The hardware RTC registers store years relative to 1968, but the driver >> wasn't consistently applying the offset when converting between >> hardware and Linux time representation. >> >> This inconsistency caused alarm rollover failures during device >> registration, with the error "alarm rollover not handled -22" in the >> logs, causing hwclock commands to fail. >> >> The ioctl interface used by the hwclock command requires proper time >> range validation that wasn't happening with the inconsistent year >> offsets. >> >> Fixes the issue by applying the year offset in all operations: >>     - Adding (RTC_MIN_YEAR - RTC_BASE_YEAR) when reading from hardware >>     - Subtracting the same offset when writing to hardware >>     - Using the same logic for both regular time and alarm operations >> >> With these changes, the hwclock command works correctly and time >> values are consistently handled across all interfaces. >> >> Signed-off-by: Alexandre Mergnat >> --- >>   drivers/rtc/rtc-mt6397.c | 13 ++++++++----- >>   1 file changed, 8 insertions(+), 5 deletions(-) >> >> diff --git a/drivers/rtc/rtc-mt6397.c b/drivers/rtc/rtc-mt6397.c >> index 692c00ff544b2..ba52e225dc8fa 100644 >> --- a/drivers/rtc/rtc-mt6397.c >> +++ b/drivers/rtc/rtc-mt6397.c >> @@ -77,7 +77,8 @@ static int __mtk_rtc_read_time(struct mt6397_rtc *rtc, >>       tm->tm_mday = data[RTC_OFFSET_DOM]; >>       tm->tm_wday = data[RTC_OFFSET_DOW]; >>       tm->tm_mon = data[RTC_OFFSET_MTH] & RTC_TC_MTH_MASK; >> -    tm->tm_year = data[RTC_OFFSET_YEAR]; >> +    /* The RTC registers store years since 1968 (hardware's base year) */ >> +    tm->tm_year = data[RTC_OFFSET_YEAR] + (RTC_MIN_YEAR - RTC_BASE_YEAR); > > This patch received a NACK because of RTC_MIN_YEAR_OFFSET. > > What you're doing here is avoiding to use the "RTC_MIN_YEAR_OFFSET" definition name > but otherwise doing the very same thing that was NACKed before. You're right sorry. In my mind, the rtc framework was working well, then I try-hard to fix the issue in this driver... but I was wrong. :( The RTC framework have issues so fixes should be in the framework directly. My next suggestion: https://lore.kernel.org/r/20250109-enable-rtc-v3-0-f003e8144419@baylibre.com -- Regards, Alexandre