linux-kernel - Re: [PATCH 1/2] parport: gsc: remove DMA leftover code

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Date:   Thu, 3 Aug 2023 10:10:45 +0200
From:   Helge Deller <deller@....de>
To:     Arnd Bergmann <arnd@...nel.org>,
        "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
        Sudip Mukherjee <sudipm.mukherjee@...il.com>
Cc:     Arnd Bergmann <arnd@...db.de>, linux-parisc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] parport: gsc: remove DMA leftover code

On 7/26/23 17:09, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@...db.de>
>
> This driver does not actually work with DMA mode, but still tries
> to call ISA DMA interface functions that are stubbed out on
> parisc, resulting in a W=1 build warning:
>
> drivers/parport/parport_gsc.c: In function 'parport_remove_chip':
> drivers/parport/parport_gsc.c:389:20: warning: suggest braces around empty body in an 'if' statement [-Wempty-body]
>    389 |    free_dma(p->dma);
>
> Remove the corresponding code as a prerequisite for turning on -Wempty-body
> by default in all kernels.
>
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

Thanks Arnd!

I've added it to the parisc for-next git tree.

Helge

> ---
>   drivers/parport/parport_gsc.c | 28 ++++------------------------
>   drivers/parport/parport_gsc.h |  7 -------
>   2 files changed, 4 insertions(+), 31 deletions(-)
>
> diff --git a/drivers/parport/parport_gsc.c b/drivers/parport/parport_gsc.c
> index 0dcc497b0449a..5e4475254bd0a 100644
> --- a/drivers/parport/parport_gsc.c
> +++ b/drivers/parport/parport_gsc.c
> @@ -28,7 +28,6 @@
>   #include <linux/sysctl.h>
>
>   #include <asm/io.h>
> -#include <asm/dma.h>
>   #include <linux/uaccess.h>
>   #include <asm/superio.h>
>
> @@ -226,9 +225,9 @@ static int parport_PS2_supported(struct parport *pb)
>
>   /* --- Initialisation code -------------------------------- */
>
> -struct parport *parport_gsc_probe_port(unsigned long base,
> +static struct parport *parport_gsc_probe_port(unsigned long base,
>   				       unsigned long base_hi, int irq,
> -				       int dma, struct parisc_device *padev)
> +				       struct parisc_device *padev)
>   {
>   	struct parport_gsc_private *priv;
>   	struct parport_operations *ops;
> @@ -250,12 +249,9 @@ struct parport *parport_gsc_probe_port(unsigned long base,
>   	}
>   	priv->ctr = 0xc;
>   	priv->ctr_writable = 0xff;
> -	priv->dma_buf = NULL;
> -	priv->dma_handle = 0;
>   	p->base = base;
>   	p->base_hi = base_hi;
>   	p->irq = irq;
> -	p->dma = dma;
>   	p->modes = PARPORT_MODE_PCSPP | PARPORT_MODE_SAFEININT;
>   	p->ops = ops;
>   	p->private_data = priv;
> @@ -286,17 +282,9 @@ struct parport *parport_gsc_probe_port(unsigned long base,
>   	if (p->irq == PARPORT_IRQ_AUTO) {
>   		p->irq = PARPORT_IRQ_NONE;
>   	}
> -	if (p->irq != PARPORT_IRQ_NONE) {
> +	if (p->irq != PARPORT_IRQ_NONE)
>   		pr_cont(", irq %d", p->irq);
>
> -		if (p->dma == PARPORT_DMA_AUTO) {
> -			p->dma = PARPORT_DMA_NONE;
> -		}
> -	}
> -	if (p->dma == PARPORT_DMA_AUTO) /* To use DMA, giving the irq
> -                                           is mandatory (see above) */
> -		p->dma = PARPORT_DMA_NONE;
> -
>   	pr_cont(" [");
>   #define printmode(x)							\
>   do {									\
> @@ -321,7 +309,6 @@ do {									\
>   			pr_warn("%s: irq %d in use, resorting to polled operation\n",
>   				p->name, p->irq);
>   			p->irq = PARPORT_IRQ_NONE;
> -			p->dma = PARPORT_DMA_NONE;
>   		}
>   	}
>
> @@ -369,8 +356,7 @@ static int __init parport_init_chip(struct parisc_device *dev)
>   		pr_info("%s: enhanced parport-modes not supported\n", __func__);
>   	}
>
> -	p = parport_gsc_probe_port(port, 0, dev->irq,
> -			/* PARPORT_IRQ_NONE */ PARPORT_DMA_NONE, dev);
> +	p = parport_gsc_probe_port(port, 0, dev->irq, dev);
>   	if (p)
>   		parport_count++;
>   	dev_set_drvdata(&dev->dev, p);
> @@ -382,16 +368,10 @@ static void __exit parport_remove_chip(struct parisc_device *dev)
>   {
>   	struct parport *p = dev_get_drvdata(&dev->dev);
>   	if (p) {
> -		struct parport_gsc_private *priv = p->private_data;
>   		struct parport_operations *ops = p->ops;
>   		parport_remove_port(p);
> -		if (p->dma != PARPORT_DMA_NONE)
> -			free_dma(p->dma);
>   		if (p->irq != PARPORT_IRQ_NONE)
>   			free_irq(p->irq, p);
> -		if (priv->dma_buf)
> -			dma_free_coherent(&priv->dev->dev, PAGE_SIZE,
> -					  priv->dma_buf, priv->dma_handle);
>   		kfree (p->private_data);
>   		parport_put_port(p);
>   		kfree (ops); /* hope no-one cached it */
> diff --git a/drivers/parport/parport_gsc.h b/drivers/parport/parport_gsc.h
> index 9301217edf12c..d447a568c2570 100644
> --- a/drivers/parport/parport_gsc.h
> +++ b/drivers/parport/parport_gsc.h
> @@ -63,8 +63,6 @@ struct parport_gsc_private {
>   	int writeIntrThreshold;
>
>   	/* buffer suitable for DMA, if DMA enabled */
> -	char *dma_buf;
> -	dma_addr_t dma_handle;
>   	struct pci_dev *dev;
>   };
>
> @@ -199,9 +197,4 @@ extern void parport_gsc_inc_use_count(void);
>
>   extern void parport_gsc_dec_use_count(void);
>
> -extern struct parport *parport_gsc_probe_port(unsigned long base,
> -						unsigned long base_hi,
> -						int irq, int dma,
> -						struct parisc_device *padev);
> -
>   #endif	/* __DRIVERS_PARPORT_PARPORT_GSC_H */