Re: [PATCH v2 1/4] spi: LS7A: Add Loongson LS7A SPI controller driver support

[zhangqing]

Hi Brown,

Thank you for your suggestions, these are achievable, I will send v3 in 
the soon.

Before sending v3, I would like to trouble you to see if this is 
correct. It has been tested locally.

On 12/08/2020 09:56 PM, Mark Brown wrote:
> On Tue, Dec 08, 2020 at 03:44:24PM +0800, Qing Zhang wrote:
>
> > v2:
> > - keep Kconfig and Makefile sorted
> > - make the entire comment a C++ one so things look more intentional
> You say this but...
>
> > +++ b/drivers/spi/spi-ls7a.c
> > @@ -0,0 +1,324 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Loongson LS7A SPI Controller driver
> > + *
> > + * Copyright (C) 2020 Loongson Technology Corporation Limited
> > + */
> ...this is still a mix of C and C++ comments?
      Replace all with //

> > +static int set_cs(struct ls7a_spi *ls7a_spi, struct spi_device  *spi, int val)
> > +{
> > +	int cs = ls7a_spi_read_reg(ls7a_spi, SFCS) & ~(0x11 << spi->chip_select);
> > +
> > +	if (spi->mode  & SPI_CS_HIGH)
> > +		val = !val;
> > +	ls7a_spi_write_reg(ls7a_spi, SFCS,
> > +		(val ? (0x11 << spi->chip_select):(0x1 << spi->chip_select)) | cs);
> > +
> > +	return 0;
> > +}
> Why not just expose this to the core and let it handle things?
>
> Please also write normal conditional statements to improve legibility.
> There's quite a lot of coding style issues in this with things like
> missing spaces
    static void ls7a_spi_set_cs(struct spi_device *spi, bool enable)
{
        struct ls7a_spi *ls7a_spi;

        int cs = ls7a_spi_read_reg(ls7a_spi, SFCS) & ~(0x11 << 
spi->chip_select));

        ls7a_spi = spi_master_get_devdata(spi->master);

        if (!!(spi->mode & SPI_CS_HIGH) == enable)
                val = (0x11 << spi->chip_select) | cs;
        else
                val = (0x1 << spi->chip_select) | cs;

        ls7a_spi_write_reg(ls7a_spi, SFCS, val);
}

     static int ls7a_spi_pci_probe---->

     +master->set_cs = ls7a_spi_set_cs;

> > +	if (t) {
> > +		hz = t->speed_hz;
> > +		if (!hz)
> > +			hz = spi->max_speed_hz;
> > +	} else
> > +		hz = spi->max_speed_hz;
> If one branch of the conditional has braces please use them on both to
> improve legibility.
>
> > +static int  ls7a_spi_transfer_one_message(struct spi_master *master,
> > +                                         struct spi_message *m)
> I don't understand why the driver is implementing transfer_one_message()
> - it looks like this is just open coding the standard loop that the
> framework provides and should just be using transfer_one().

static int  ls7a_spi_transfer_one(struct spi_master *master,
                      struct spi_device *spi,
                                  struct spi_transfer *t)
{
    struct ls7a_spi *ls7a_spi;
    int param, status;

    ls7a_spi = spi_master_get_devdata(master);

    spin_lock(&ls7a_spi->lock);
    param = ls7a_spi_read_reg(ls7a_spi, PARA);
    ls7a_spi_write_reg(ls7a_spi, PARA, param&~1);
    spin_unlock(&ls7a_spi->lock);

        status = ls7a_spi_do_transfer(ls7a_spi, spi, t);
        if(status < 0)
                return status;

        if(t->len)
        r = ls7a_spi_write_read(spi, t);

        spin_lock(&ls7a_spi->lock);
    ls7a_spi_write_reg(ls7a_spi, PARA, param);
    spin_unlock(&ls7a_spi->lock);

    return status;
}

  static int ls7a_spi_pci_probe---->

 - master->transfer_one_message = ls7a_spi_transfer_one_message;
 +master->transfer_one = ls7a_spi_transfer_one;
> > +		r = ls7a_spi_write_read(spi, t);
> > +		if (r < 0) {
> > +			status = r;
> > +			goto error;
> > +			}
> The indentation here isn't following the kernel coding style.
>
> > +	master = spi_alloc_master(&pdev->dev, sizeof(struct ls7a_spi));
> > +	if (!master)
> > +		return -ENOMEM;
> Why not use devm_ here?

- master = spi_alloc_master(&pdev->dev, sizeof(struct ls7a_spi));

  error:
- spi_put_master(master);

+ master = devm_spi_alloc_master(&pdev->dev, sizeof(struct ls7a_spi));

> > +	ret = devm_spi_register_master(dev, master);
> > +	if (ret)
> > +		goto err_free_master;
> The driver uses devm_spi_register_master() here but...
>
> > +static void ls7a_spi_pci_remove(struct pci_dev *pdev)
> > +{
> > +	struct spi_master *master = pci_get_drvdata(pdev);
> > +	struct ls7a_spi *spi;
> > +
> > +	spi = spi_master_get_devdata(master);
> > +	if (!spi)
> > +		return;
> > +
> > +	pci_release_regions(pdev);
> ...releases the PCI regions in the remove() function before the SPI
> controller is freed so the controller could still be active.

     static void ls7a_spi_pci_remove(struct pci_dev *pdev)
{
        struct spi_master *master = pci_get_drvdata(pdev);

     + spi_unregister_master(master);
        pci_release_regions(pdev);
}

Thanks,

-Qing