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[62.78.225.252]) by smtp.gmail.com with ESMTPSA id y11-20020a05651c020b00b002a8a8f2dc89sm5907418ljn.72.2023.05.03.03.01.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 03 May 2023 03:01:36 -0700 (PDT) Date: Wed, 3 May 2023 13:01:32 +0300 From: Matti Vaittinen To: Matti Vaittinen , Matti Vaittinen Cc: Matti Vaittinen , Jonathan Cameron , Lars-Peter Clausen , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2] iio: bu27034: Ensure reset is written Message-ID: MIME-Version: 1.0 Content-Disposition: inline X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM, RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1764869305454893135?= X-GMAIL-MSGID: =?utf-8?q?1764869305454893135?= The reset bit must be always written to the hardware no matter what value is in a cache or register. Ensure this by using regmap_write_bits() instead of the regmap_update_bits(). Furthermore, the RESET bit may be self-clearing, so mark the SYSTEM_CONTROL register volatile to guarantee we do also read the right state - should we ever need to read it. Signed-off-by: Matti Vaittinen Fixes: e52afbd61039 ("iio: light: ROHM BU27034 Ambient Light Sensor") --- Changelog: v1 => v2: - Fix SoB tag I haven't verified if the reset bit is self-clearin as I did temporarily give away the HW. In worst case the bit is not self clearing - but we don't really get performance penalty even if we set the register volatile because the SYSTEM_CONTROL register only has the part-ID and the reset fields. The part-id is only read once at probe. --- drivers/iio/light/rohm-bu27034.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) base-commit: 7fcbd72176076c44b47e8f68f0223c02c411f420 diff --git a/drivers/iio/light/rohm-bu27034.c b/drivers/iio/light/rohm-bu27034.c index 25c9b79574a5..740ebd86b6e5 100644 --- a/drivers/iio/light/rohm-bu27034.c +++ b/drivers/iio/light/rohm-bu27034.c @@ -231,6 +231,9 @@ struct bu27034_result { static const struct regmap_range bu27034_volatile_ranges[] = { { + .range_min = BU27034_REG_SYSTEM_CONTROL, + .range_max = BU27034_REG_SYSTEM_CONTROL, + }, { .range_min = BU27034_REG_MODE_CONTROL4, .range_max = BU27034_REG_MODE_CONTROL4, }, { @@ -1272,7 +1275,7 @@ static int bu27034_chip_init(struct bu27034_data *data) int ret, sel; /* Reset */ - ret = regmap_update_bits(data->regmap, BU27034_REG_SYSTEM_CONTROL, + ret = regmap_write_bits(data->regmap, BU27034_REG_SYSTEM_CONTROL, BU27034_MASK_SW_RESET, BU27034_MASK_SW_RESET); if (ret) return dev_err_probe(data->dev, ret, "Sensor reset failed\n");