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Mon, 9 Nov 2026 23:09:07 -0600 From: Dileep Kumar Nagavarapu To: Jonathan Cameron , David Lechner , =?UTF-8?q?Nuno=20S=C3=A1?= , Andy Shevchenko , Michal Simek , Conall O'Griofa CC: , , , , Dileep Kumar Nagavarapu , Sai Krishna Potthuri , Joshua Crofts Subject: [PATCH v5 11/16] iio: adc: xilinx-xadc: Add clarifying comments Date: Tue, 10 Nov 2026 10:31:56 +0530 Message-ID: <20261110050201.1850399-12-dileepkumar.nagavarapu@amd.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20261110050201.1850399-1-dileepkumar.nagavarapu@amd.com> References: <20261110050201.1850399-1-dileepkumar.nagavarapu@amd.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BY1PEPF0002695A:EE_|IA0PPF8CAB220A1:EE_ X-MS-Office365-Filtering-Correlation-Id: f0c95e4b-4c47-4d58-ba85-08df3ee8c3ab X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|82310400026|36860700016|23010399003|376014|18002099003|22082099003|6133799003|10067099003|11063799006|261102123227099003|261028144727099003|261022105027099003|261009223027099003|261022075727099003|261021121427099003|261021123027099003|56012099006|261026140227099003; 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No functional change intended. Co-developed-by: Sai Krishna Potthuri Signed-off-by: Sai Krishna Potthuri Reviewed-by: Joshua Crofts Signed-off-by: Dileep Kumar Nagavarapu --- drivers/iio/adc/xilinx-xadc-core.c | 9 +++++++++ drivers/iio/adc/xilinx-xadc.h | 2 ++ 2 files changed, 11 insertions(+) diff --git a/drivers/iio/adc/xilinx-xadc-core.c b/drivers/iio/adc/xilinx-xadc-core.c index 12df599358b8..9269b63d0f2c 100644 --- a/drivers/iio/adc/xilinx-xadc-core.c +++ b/drivers/iio/adc/xilinx-xadc-core.c @@ -158,6 +158,11 @@ static void xadc_zynq_drain_fifo(struct xadc *xadc) xadc_read_reg(xadc, XADC_ZYNQ_REG_STATUS, &status); + /* + * Reading XADC_ZYNQ_REG_DFIFO pops one entry from the data FIFO. + * The loop therefore removes one pending entry per iteration and + * terminates once the hardware reports the FIFO empty. + */ while (!(status & XADC_ZYNQ_STATUS_DFIFOE)) { xadc_read_reg(xadc, XADC_ZYNQ_REG_DFIFO, &tmp); xadc_read_reg(xadc, XADC_ZYNQ_REG_STATUS, &status); @@ -241,6 +246,10 @@ static int xadc_zynq_read_adc_reg(struct xadc *xadc, unsigned int reg, u16 *val) static unsigned int xadc_zynq_transform_alarm(unsigned int alarm) { + /* + * Reorder the Zynq PS-XADC alarm bits defined in UG585 to match the common + * XADC driver alarm layout. + */ return ((alarm & 0x80) >> 4) | ((alarm & 0x78) << 1) | (alarm & 0x07); } diff --git a/drivers/iio/adc/xilinx-xadc.h b/drivers/iio/adc/xilinx-xadc.h index 90fa3e77b1a5..1bbc19ac6333 100644 --- a/drivers/iio/adc/xilinx-xadc.h +++ b/drivers/iio/adc/xilinx-xadc.h @@ -60,7 +60,9 @@ struct xadc { unsigned int zynq_intmask; struct delayed_work zynq_unmask_work; + /* Serializes register access and device configuration updates */ struct mutex mutex; + /* Protects interrupt state and FIFO operations */ spinlock_t lock; struct completion completion; -- 2.34.1