linux-kernel - Re: [PATCH 01/11] spi/pxa2xx: allow building on a 64-bit kernel

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Date:	Tue, 8 Jan 2013 11:27:45 +0800
From:	Eric Miao <eric.y.miao@...il.com>
To:	Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc:	linux-kernel <linux-kernel@...r.kernel.org>,
	Grant Likely <grant.likely@...retlab.ca>,
	Linus Walleij <linus.walleij@...aro.org>,
	Russell King <linux@....linux.org.uk>,
	Haojian Zhuang <haojian.zhuang@...il.com>,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	chao.bi@...el.com, "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: Re: [PATCH 01/11] spi/pxa2xx: allow building on a 64-bit kernel

On Mon, Jan 7, 2013 at 6:44 PM, Mika Westerberg
<mika.westerberg@...ux.intel.com> wrote:
> In addition fix following warnings seen when compiling 64-bit:
>
> drivers/spi/spi-pxa2xx.c: In function ‘map_dma_buffers’: drivers/spi/spi-pxa2xx.c:384:7: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
> drivers/spi/spi-pxa2xx.c:384:40: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
> drivers/spi/spi-pxa2xx.c: In function ‘pxa2xx_spi_probe’:
> drivers/spi/spi-pxa2xx.c:1572:34: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
> drivers/spi/spi-pxa2xx.c:1572:34: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
> drivers/spi/spi-pxa2xx.c:1572:34: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
> drivers/spi/spi-pxa2xx.c:1572:27: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
>
> Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
> ---
>  drivers/spi/Kconfig      |    4 ++--
>  drivers/spi/spi-pxa2xx.c |    5 ++---
>  2 files changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
> index 2e188e1..a90393d 100644
> --- a/drivers/spi/Kconfig
> +++ b/drivers/spi/Kconfig
> @@ -299,7 +299,7 @@ config SPI_PPC4xx
>
>  config SPI_PXA2XX
>         tristate "PXA2xx SSP SPI master"
> -       depends on (ARCH_PXA || (X86_32 && PCI)) && EXPERIMENTAL
> +       depends on ARCH_PXA || PCI
>         select PXA_SSP if ARCH_PXA
>         help
>           This enables using a PXA2xx or Sodaville SSP port as a SPI master
> @@ -307,7 +307,7 @@ config SPI_PXA2XX
>           additional documentation can be found a Documentation/spi/pxa2xx.
>
>  config SPI_PXA2XX_PCI
> -       def_bool SPI_PXA2XX && X86_32 && PCI
> +       def_tristate SPI_PXA2XX && PCI
>

Generally looks good to me, I think we could split the changes to

* Kconfig (adding 64-bit support or removing restrictions of X86_32
for the driver)
* and to spi-pxa2xx.c (mostly to handle the alignment warnings)

>  config SPI_RSPI
>         tristate "Renesas RSPI controller"
> diff --git a/drivers/spi/spi-pxa2xx.c b/drivers/spi/spi-pxa2xx.c
> index 5c8c4f5..7fac65d 100644
> --- a/drivers/spi/spi-pxa2xx.c
> +++ b/drivers/spi/spi-pxa2xx.c
> @@ -47,7 +47,7 @@ MODULE_ALIAS("platform:pxa2xx-spi");
>
>  #define DMA_INT_MASK           (DCSR_ENDINTR | DCSR_STARTINTR | DCSR_BUSERR)
>  #define RESET_DMA_CHANNEL      (DCSR_NODESC | DMA_INT_MASK)
> -#define IS_DMA_ALIGNED(x)      ((((u32)(x)) & 0x07) == 0)
> +#define IS_DMA_ALIGNED(x)      IS_ALIGNED((unsigned long)x, DMA_ALIGNMENT)

OK.

>  #define MAX_DMA_LEN            8191
>  #define DMA_ALIGNMENT          8
>
> @@ -1569,8 +1569,7 @@ static int pxa2xx_spi_probe(struct platform_device *pdev)
>         master->transfer = transfer;
>
>         drv_data->ssp_type = ssp->type;
> -       drv_data->null_dma_buf = (u32 *)ALIGN((u32)(drv_data +
> -                                               sizeof(struct driver_data)), 8);
> +       drv_data->null_dma_buf = (u32 *)PTR_ALIGN(drv_data + 1, 8);

Hmm... the original code seems to have big problem and interestingly no
one has reported the issue, possibly due to null_dma_buf being seldomly
used.

However, it's still a bit obscure to have 'drv_data + 1', 'drv_data[1]' might
be a bit better for readability.

And it'll be better to have DMA_ALIGNTMENT here instead of a hard-coded
constant '8'.
    u

>
>         drv_data->ioaddr = ssp->mmio_base;
>         drv_data->ssdr_physical = ssp->phys_base + SSDR;
> --
> 1.7.10.4
>
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