2017-09-17 14:25:19

by Stefan Brüns

[permalink] [raw]
Subject: [PATCH] dmaengine: edma: Reject slave configs using a buswidth of 8 and larger

The driver would happily accept buswidth of 16/32/64 bytes and program
garbage to its registers.

Signed-off-by: Stefan Brüns <[email protected]>
---
drivers/dma/edma.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c
index 3879f80a4815..c944ea339425 100644
--- a/drivers/dma/edma.c
+++ b/drivers/dma/edma.c
@@ -887,8 +887,8 @@ static int edma_slave_config(struct dma_chan *chan,
{
struct edma_chan *echan = to_edma_chan(chan);

- if (cfg->src_addr_width == DMA_SLAVE_BUSWIDTH_8_BYTES ||
- cfg->dst_addr_width == DMA_SLAVE_BUSWIDTH_8_BYTES)
+ if (cfg->src_addr_width >= DMA_SLAVE_BUSWIDTH_8_BYTES ||
+ cfg->dst_addr_width >= DMA_SLAVE_BUSWIDTH_8_BYTES)
return -EINVAL;

memcpy(&echan->cfg, cfg, sizeof(echan->cfg));
--
2.14.1


2017-09-21 17:14:13

by Vinod Koul

[permalink] [raw]
Subject: Re: [PATCH] dmaengine: edma: Reject slave configs using a buswidth of 8 and larger

On Sun, Sep 17, 2017 at 04:25:10PM +0200, Stefan Br?ns wrote:
> The driver would happily accept buswidth of 16/32/64 bytes and program
> garbage to its registers.

Peter?

>
> Signed-off-by: Stefan Br?ns <[email protected]>
> ---
> drivers/dma/edma.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c
> index 3879f80a4815..c944ea339425 100644
> --- a/drivers/dma/edma.c
> +++ b/drivers/dma/edma.c
> @@ -887,8 +887,8 @@ static int edma_slave_config(struct dma_chan *chan,
> {
> struct edma_chan *echan = to_edma_chan(chan);
>
> - if (cfg->src_addr_width == DMA_SLAVE_BUSWIDTH_8_BYTES ||
> - cfg->dst_addr_width == DMA_SLAVE_BUSWIDTH_8_BYTES)
> + if (cfg->src_addr_width >= DMA_SLAVE_BUSWIDTH_8_BYTES ||
> + cfg->dst_addr_width >= DMA_SLAVE_BUSWIDTH_8_BYTES)
> return -EINVAL;
>
> memcpy(&echan->cfg, cfg, sizeof(echan->cfg));
> --
> 2.14.1
>

--
~Vinod

2017-09-21 18:29:29

by Peter Ujfalusi

[permalink] [raw]
Subject: Re: [PATCH] dmaengine: edma: Reject slave configs using a buswidth of 8 and larger




Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

On 2017-09-21 20:17, Vinod Koul wrote:
> On Sun, Sep 17, 2017 at 04:25:10PM +0200, Stefan Brüns wrote:
>> The driver would happily accept buswidth of 16/32/64 bytes and program
>> garbage to its registers.
>
> Peter?

Well, eDMA as such has no limitation on the buswidth, the addr_width
become ACNT, counter for the inner loop - which we use to represent the
word length. In theory we could support 32K-1 long word with eDMA, which
we actually do in case of memcpy.

But the driver does state that it supports bus width of 1, 2, 3 and 4 bytes.

These are form the past and I never felt the need to check them.

I think it is fine to reject salve config when asking for longer dev
width. I might revisit later if the need comes..

Acked-by: Peter Ujfalusi <[email protected]>

>
>>
>> Signed-off-by: Stefan Brüns <[email protected]>
>> ---
>> drivers/dma/edma.c | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c
>> index 3879f80a4815..c944ea339425 100644
>> --- a/drivers/dma/edma.c
>> +++ b/drivers/dma/edma.c
>> @@ -887,8 +887,8 @@ static int edma_slave_config(struct dma_chan *chan,
>> {
>> struct edma_chan *echan = to_edma_chan(chan);
>>
>> - if (cfg->src_addr_width == DMA_SLAVE_BUSWIDTH_8_BYTES ||
>> - cfg->dst_addr_width == DMA_SLAVE_BUSWIDTH_8_BYTES)
>> + if (cfg->src_addr_width >= DMA_SLAVE_BUSWIDTH_8_BYTES ||
>> + cfg->dst_addr_width >= DMA_SLAVE_BUSWIDTH_8_BYTES)
>> return -EINVAL;
>>
>> memcpy(&echan->cfg, cfg, sizeof(echan->cfg));
>> --
>> 2.14.1
>>
>

- Péter


2017-09-22 06:16:15

by Peter Ujfalusi

[permalink] [raw]
Subject: Re: [PATCH] dmaengine: edma: Reject slave configs using a buswidth of 8 and larger

Stefan, Vinod,


Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

On 2017-09-21 21:29, Peter Ujfalusi wrote:
>
>
> On 2017-09-21 20:17, Vinod Koul wrote:
>> On Sun, Sep 17, 2017 at 04:25:10PM +0200, Stefan Brüns wrote:
>>> The driver would happily accept buswidth of 16/32/64 bytes and program
>>> garbage to its registers.
>>
>> Peter?
>
> Well, eDMA as such has no limitation on the buswidth, the addr_width
> become ACNT, counter for the inner loop - which we use to represent the
> word length. In theory we could support 32K-1 long word with eDMA, which
> we actually do in case of memcpy.
>
> But the driver does state that it supports bus width of 1, 2, 3 and 4 bytes.
>
> These are form the past and I never felt the need to check them.
>
> I think it is fine to reject salve config when asking for longer dev
> width. I might revisit later if the need comes..
>
> Acked-by: Peter Ujfalusi <[email protected]>

If it is not too late, I have second thoughts about this..
It might be better to remove the src_addr_width/dst_addr_width check
from edma_slave_config() and add all DMA_SLAVE_BUSWIDTH_* to
EDMA_DMA_BUSWIDTHS.

>
>>
>>>
>>> Signed-off-by: Stefan Brüns <[email protected]>
>>> ---
>>> drivers/dma/edma.c | 4 ++--
>>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c
>>> index 3879f80a4815..c944ea339425 100644
>>> --- a/drivers/dma/edma.c
>>> +++ b/drivers/dma/edma.c
>>> @@ -887,8 +887,8 @@ static int edma_slave_config(struct dma_chan *chan,
>>> {
>>> struct edma_chan *echan = to_edma_chan(chan);
>>>
>>> - if (cfg->src_addr_width == DMA_SLAVE_BUSWIDTH_8_BYTES ||
>>> - cfg->dst_addr_width == DMA_SLAVE_BUSWIDTH_8_BYTES)
>>> + if (cfg->src_addr_width >= DMA_SLAVE_BUSWIDTH_8_BYTES ||
>>> + cfg->dst_addr_width >= DMA_SLAVE_BUSWIDTH_8_BYTES)
>>> return -EINVAL;
>>>
>>> memcpy(&echan->cfg, cfg, sizeof(echan->cfg));
>>> --
>>> 2.14.1
>>>
>>
>
> - Péter
>

- Péter


2017-09-22 08:39:47

by Vinod Koul

[permalink] [raw]
Subject: Re: [PATCH] dmaengine: edma: Reject slave configs using a buswidth of 8 and larger

On Fri, Sep 22, 2017 at 09:16:13AM +0300, Peter Ujfalusi wrote:
> Stefan, Vinod,
>
>
> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
>
> On 2017-09-21 21:29, Peter Ujfalusi wrote:
> >
> >
> > On 2017-09-21 20:17, Vinod Koul wrote:
> >> On Sun, Sep 17, 2017 at 04:25:10PM +0200, Stefan Br?ns wrote:
> >>> The driver would happily accept buswidth of 16/32/64 bytes and program
> >>> garbage to its registers.
> >>
> >> Peter?
> >
> > Well, eDMA as such has no limitation on the buswidth, the addr_width
> > become ACNT, counter for the inner loop - which we use to represent the
> > word length. In theory we could support 32K-1 long word with eDMA, which
> > we actually do in case of memcpy.
> >
> > But the driver does state that it supports bus width of 1, 2, 3 and 4 bytes.
> >
> > These are form the past and I never felt the need to check them.
> >
> > I think it is fine to reject salve config when asking for longer dev
> > width. I might revisit later if the need comes..
> >
> > Acked-by: Peter Ujfalusi <[email protected]>
>
> If it is not too late, I have second thoughts about this..
> It might be better to remove the src_addr_width/dst_addr_width check
> from edma_slave_config() and add all DMA_SLAVE_BUSWIDTH_* to
> EDMA_DMA_BUSWIDTHS.

fine by me, pls send updated..

--
~Vinod