On Tue, 18 May 2021 11:39:49 +0200
[off-list ref] wrote:

+/**
+ * spi_mem_poll_status() - Poll memory device status
+ * @mem: SPI memory device
+ * @op: the memory operation to execute
+ * @mask: status bitmask to ckeck
+ * @match: (status & mask) expected value
+ * @initial_delay_us: delay in us before starting to poll
+ * @polling_delay_us: time to sleep between reads in us
+ * @timeout_ms: timeout in milliseconds
+ *
+ * This function send a polling status request to the controller driver
+ *
+ * Return: 0 in case of success, -ETIMEDOUT in case of error,
+ *         -EOPNOTSUPP if not supported.
+ */
+int spi_mem_poll_status(struct spi_mem *mem,
+			const struct spi_mem_op *op,
+			u16 mask, u16 match,
+			unsigned long initial_delay_us,
+			unsigned long polling_delay_us,
+			u16 timeout_ms)
+{
+	struct spi_controller *ctlr = mem->spi->controller;
+	int ret = -EOPNOTSUPP;
+	int read_status_ret;
+	u16 status;
+
+	if (op->data.nbytes < 1 || op->data.nbytes > 2)
+		return -EINVAL;

We should also make sure this is a read operation.

+
+	if (ctlr->mem_ops && ctlr->mem_ops->poll_status) {
+		ret = spi_mem_access_start(mem);
+		if (ret)
+			return ret;
+
+		ret = ctlr->mem_ops->poll_status(mem, op, mask, match,
+						 initial_delay_us, polling_delay_us,
+						 timeout_ms);
+
+		spi_mem_access_end(mem);
+	}
+
+	if (ret == -EOPNOTSUPP) {
+		if (!spi_mem_supports_op(mem, op))
+			return ret;
+
+		if (initial_delay_us < 10)
+			udelay(initial_delay_us);
+		else
+			usleep_range((initial_delay_us >> 2) + 1,
+				     initial_delay_us);
+
+		ret = read_poll_timeout(spi_mem_read_status, read_status_ret,
+					(read_status_ret || ((status) & mask) == match),
+					polling_delay_us, timeout_ms * 1000, false, mem,
+					op, &status);
+		if (read_status_ret)
+			return read_status_ret;
+	}
+
+	return ret;
+}

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