linux-kernel - Re: [PATCH v2 1/2] Add Cadence XSPI driver

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Message-ID: <20200220082354.GA15619@global.cadence.com>
Date:   Thu, 20 Feb 2020 09:23:56 +0100
From:   Konrad Kociolek <konrad@...ence.com>
To:     Mark Brown <broonie@...nel.org>
CC:     <linux-kernel@...r.kernel.org>, <linux-spi@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] Add Cadence XSPI driver

The 02/10/2020 19:16, Mark Brown wrote:
>EXTERNAL MAIL
>
>
>On Tue, Jan 28, 2020 at 01:41:57PM +0100, Konrad Kociolek wrote:
>
>>  	  Enables Xilinx GQSPI controller driver for Zynq UltraScale+ MPSoC.
>>
>> +config SPI_CADENCE_XSPI
>> +	tristate "Cadence XSPI controller"
>> +	depends on (OF || COMPILE_TEST) && HAS_IOMEM
>> +	help
>> +	  Enable support for the Cadence XSPI Flash controller.
>> +
>> +	  Cadence XSPI is a specialized controller for connecting an SPI
>> +	  Flash over upto 8bit wide bus. Enable this option if you have a
>> +	  device with a Cadence XSPI controller and want to access the
>> +	  Flash as an MTD device.
>> +
>>  #
>>  # Add new SPI master controllers in alphabetical order above this line
>>  #
>
>Please keep Kconfig and Makefile alphabetically sorted as the comment in
>the context from the diff says.  :/
>
What I see is Kconfig is first and Makefile is second file in diff,
according to:
  drivers/spi/Kconfig            |  11 +
  drivers/spi/Makefile           |   1 +
Is that wrong?
>> --- /dev/null
>> +++ b/drivers/spi/spi-cadence-xspi.c
>> @@ -0,0 +1,895 @@
>> +// SPDX-License-Identifier: GPL-2.0+
>> +/*
>> + * Cadence XSPI flash controller driver
>
>Please make the entire comment a C++ so things look more intentional.
>
>> +	dev_info(cdns_xspi->dev,
>> +		"Running PHY training for read_dqs_delay parameter\n");
>
>This print is just noise, please remove it.
>
>> +static int cdns_xspi_setup(struct spi_device *spi_dev)
>> +{
>> +	if (spi_dev->chip_select > spi_dev->master->num_chipselect) {
>> +		dev_err(&spi_dev->dev,
>> +			"%d chip-select is out of range\n",
>> +			spi_dev->chip_select);
>> +		return -EINVAL;
>> +	}
>
>If this isn't already being validated by the core it should be and this
>function can be removed.
>
>> +	irq_status = readl(cdns_xspi->iobase + CDNS_XSPI_INTR_STATUS_REG);
>> +	if (irq_status) {
>> +		writel(irq_status,
>> +			cdns_xspi->iobase + CDNS_XSPI_INTR_STATUS_REG);
>
>This unconditionally acknowledges everything, even things we don't
>understand.  If the hardware is generating unexpected interrupt statuses
>we should probably warn.
>
>> +static void cdns_xspi_print_phy_config(struct cdns_xspi_dev *cdns_xspi)
>> +{
>> +	struct device *dev = cdns_xspi->dev;
>> +
>> +	dev_info(dev, "PHY configuration\n");
>> +	dev_info(dev, "   * xspi_dll_phy_ctrl: %08x\n",
>> +		readl(cdns_xspi->iobase + CDNS_XSPI_DLL_PHY_CTRL));
>> +	dev_info(dev, "   * phy_dq_timing: %08x\n",
>> +		readl(cdns_xspi->auxbase + CDNS_XSPI_CCP_PHY_DQ_TIMING));
>> +	dev_info(dev, "   * phy_dqs_timing: %08x\n",
>> +		readl(cdns_xspi->auxbase + CDNS_XSPI_CCP_PHY_DQS_TIMING));
>> +	dev_info(dev, "   * phy_gate_loopback_ctrl: %08x\n",
>> +		readl(cdns_xspi->auxbase + CDNS_XSPI_CCP_PHY_GATE_LPBCK_CTRL));
>> +	dev_info(dev, "   * phy_dll_slave_ctrl: %08x\n",
>> +		readl(cdns_xspi->auxbase + CDNS_XSPI_CCP_PHY_DLL_SLAVE_CTRL));
>> +}
>
>This seems pretty verbose for an individual device...  If this is needed
>for diagnostics perhaps put it in sysfs or debugfs where it'll be
>accessible even if the log wraps?
>
>> +err_no_mem:
>> +	dev_err(dev, "Failed to probe Cadence XSPI controller driver\n");
>
>Not sure this is adding anything over the individual error messages on
>specific failures.
>
>> +#ifdef CONFIG_OF
>> +static const struct of_device_id cdns_xspi_of_match[] = {
>> +	{
>> +		.compatible = "cdns,xspi-nor-fpga",
>> +	},
>
>Why -fpga?
This is because this driver was tested only on FPGA board.
This driver was not tested for ASIC version as PHY
initialization algorithm is differ.



-- 
--
Konrad Kociolek