2009-06-17 02:15:23

by FUJITA Tomonori

Subject: [PATCH] parport_pc: set properly the dma_mask for parport_pc device

parport_pc_probe_port() creates the own 'parport_pc' device if the
device argument is NULL. Then parport_pc_probe_port() doesn't
initialize the dma_mask and coherent_dma_mask of the device and calls
dma_alloc_coherent with it. dma_alloc_coherent fails because
dma_alloc_coherent() doesn't accept the uninitialized dma_mask:

http://lkml.org/lkml/2009/6/16/150

Long ago, X86_32 and X86_64 had the own dma_alloc_coherent
implementations; X86_32 accepted a device having dma_mask that is not
initialized however X86_64 didn't. When we merged them, we chose to
prohibit a device having dma_mask that is not initialized. I think
that it's good to require drivers to set up dma_mask (and
coherent_dma_mask) properly if the drivers want DMA.

Signed-off-by: FUJITA Tomonori <[email protected]>
Reported-by: Malcom Blaney <[email protected]>
Tested-by: Malcom Blaney <[email protected]>
Cc: [email protected]
---
drivers/parport/parport_pc.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/drivers/parport/parport_pc.c b/drivers/parport/parport_pc.c
index 151bf5b..1af57b7 100644
--- a/drivers/parport/parport_pc.c
+++ b/drivers/parport/parport_pc.c
@@ -2271,6 +2271,9 @@ struct parport *parport_pc_probe_port(unsigned long int base,
if (IS_ERR(pdev))
return NULL;
dev = &pdev->dev;
+
+ dev->coherent_dma_mask = DMA_BIT_MASK(24);
+ dev->dma_mask = &dev->coherent_dma_mask;
}

ops = kmalloc(sizeof(struct parport_operations), GFP_KERNEL);
--
1.6.0.6

2009-06-17 02:37:59

by Malcom Blaney

Subject: Re: [PATCH] parport_pc: set properly the dma_mask for parport_pc device

I used this with a patch I worked on a few years ago to fix ECP reads
from the parport.

If anyone is interested it can be found at:
http://lists.infradead.org/pipermail/linux-parport/2007-October/000614.html

2009/6/17 FUJITA Tomonori <[email protected]>:
> parport_pc_probe_port() creates the own 'parport_pc' device if the
> device argument is NULL. Then parport_pc_probe_port() doesn't
> initialize the dma_mask and coherent_dma_mask of the device and calls
> dma_alloc_coherent with it. dma_alloc_coherent fails because
> dma_alloc_coherent() doesn't accept the uninitialized dma_mask:
>
> http://lkml.org/lkml/2009/6/16/150
>
> Long ago, X86_32 and X86_64 had the own dma_alloc_coherent
> implementations; X86_32 accepted a device having dma_mask that is not
> initialized however X86_64 didn't. When we merged them, we chose to
> prohibit a device having dma_mask that is not initialized. I think
> that it's good to require drivers to set up dma_mask (and
> coherent_dma_mask) properly if the drivers want DMA.
>
> Signed-off-by: FUJITA Tomonori <[email protected]>
> Reported-by: Malcom Blaney <[email protected]>
> Tested-by: Malcom Blaney <[email protected]>
> Cc: [email protected]
> ---
> ?drivers/parport/parport_pc.c | ? ?3 +++
> ?1 files changed, 3 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/parport/parport_pc.c b/drivers/parport/parport_pc.c
> index 151bf5b..1af57b7 100644
> --- a/drivers/parport/parport_pc.c
> +++ b/drivers/parport/parport_pc.c
> @@ -2271,6 +2271,9 @@ struct parport *parport_pc_probe_port(unsigned long int base,
> ? ? ? ? ? ? ? ?if (IS_ERR(pdev))
> ? ? ? ? ? ? ? ? ? ? ? ?return NULL;
> ? ? ? ? ? ? ? ?dev = &pdev->dev;
> +
> + ? ? ? ? ? ? ? dev->coherent_dma_mask = DMA_BIT_MASK(24);
> + ? ? ? ? ? ? ? dev->dma_mask = &dev->coherent_dma_mask;
> ? ? ? ?}
>
> ? ? ? ?ops = kmalloc(sizeof(struct parport_operations), GFP_KERNEL);
> --
> 1.6.0.6
>
>