linux-kernel - Re: [PATCH v2 1/3] spi: spi-mem: add automatic poll status functions

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Date:   Mon, 17 May 2021 09:41:40 +0200
From:   Boris Brezillon <boris.brezillon@...labora.com>
To:     <patrice.chotard@...s.st.com>
Cc:     Mark Brown <broonie@...nel.org>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Vignesh Raghavendra <vigneshr@...com>,
        <linux-mtd@...ts.infradead.org>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        <linux-spi@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <christophe.kerello@...s.st.com>
Subject: Re: [PATCH v2 1/3] spi: spi-mem: add automatic poll status
 functions

On Fri, 7 May 2021 15:17:54 +0200
<patrice.chotard@...s.st.com> 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
> + * @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, u16 timeout_ms)

Maybe you should pass a delay_us too, to poll the status at the right
rate in the SW-based case (can also be used by drivers if they need to
configure the polling rate). You could also add an initial_delay_us to
avoid polling the status too early: an erase operation will take longer
than a write which will take longer than a read. No need to check the
status just after issuing the command, especially if the polling is
done in SW. Those 2 arguments should also be passed to the driver.

> +{
> +	struct spi_controller *ctlr = mem->spi->controller;
> +	unsigned long ms;
> +	int ret = -EOPNOTSUPP;
> +	int exec_op_ret;
> +	u16 *status;
> +
> +	if (!spi_mem_supports_op(mem, op))
> +		return ret;
> +
> +	if (ctlr->mem_ops && ctlr->mem_ops->poll_status) {
> +		ret = spi_mem_access_start(mem);
> +		if (ret)
> +			return ret;
> +
> +		reinit_completion(&ctlr->xfer_completion);
> +
> +		ret = ctlr->mem_ops->poll_status(mem, op, mask, match,
> +						 timeout_ms);
> +
> +		ms = wait_for_completion_timeout(&ctlr->xfer_completion,
> +						 msecs_to_jiffies(timeout_ms));
> +
> +		spi_mem_access_end(mem);
> +		if (!ms)
> +			return -ETIMEDOUT;
> +	} else {
> +		status = (u16 *)op->data.buf.in;
> +		ret = read_poll_timeout(spi_mem_exec_op, exec_op_ret,
> +					((*status) & mask) == match, 20,
> +					timeout_ms * 1000, false, mem, op);
> +		if (exec_op_ret)
> +			return exec_op_ret;
> +	}
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(spi_mem_poll_status);
> +