Re: [PATCH v2] OMAP: DMA: Add API for setting channel dest addr
Venkatraman S writes:
> Manjunath,
>
> On Tue, Mar 2, 2010 at 7:06 PM, Manjunatha GK wrote:
>> The new API - omap_set_dma_dst_pos(int lch, int value) is added
>> for setting channel destination address in CPC/CDAC register
>>
>> Cc: Tony Lindgren
>> Cc: Santosh Shilimkar
>> Cc: S, Venkatraman
>> Signed-off-by: Manjunatha GK
>> Signed-off-by: Govindraj R
>> ---
>> arch/arm/plat-omap/dma.c | 17 +
>> arch/arm/plat-omap/include/plat/dma.h | 1 +
>> 2 files changed, 18 insertions(+), 0 deletions(-)
>>
>> diff --git a/arch/arm/plat-omap/dma.c b/arch/arm/plat-omap/dma.c
>> index 2ab224c..c73f11a 100644
>> --- a/arch/arm/plat-omap/dma.c
>> +++ b/arch/arm/plat-omap/dma.c
>> @@ -1109,6 +1109,23 @@ dma_addr_t omap_get_dma_dst_pos(int lch)
>> }
>> EXPORT_SYMBOL(omap_get_dma_dst_pos);
>>
>> +/**
>> + * omap_set_dma_dst_pos() - Set DMA channel destination address
>> + * @arg1: lch DMA logical channel number
>> + * @arg2: value Value to write into CDAC register
>> + *
>> + * Writes "value" into the register CPC/CDAC
>> + */
>> +void omap_set_dma_dst_pos(int lch, int value)
>> +{
>> + if (cpu_is_omap15xx())
>> + dma_write(value, CPC(lch));
>> + else
>> + dma_write(value, CDAC(lch));
>> +
>> +}
>> +EXPORT_SYMBOL(omap_set_dma_dst_pos);
>> +
>> int omap_get_dma_active_status(int lch)
>> {
>> return (dma_read(CCR(lch)) & OMAP_DMA_CCR_EN) != 0;
>> diff --git a/arch/arm/plat-omap/include/plat/dma.h
>> b/arch/arm/plat-omap/include/plat/dma.h
>> index 02232ca..3b6e43e 100644
>> --- a/arch/arm/plat-omap/include/plat/dma.h
>> +++ b/arch/arm/plat-omap/include/plat/dma.h
>> @@ -509,6 +509,7 @@ extern int omap_set_dma_callback(int lch,
>> void *data);
>> extern dma_addr_t omap_get_dma_src_pos(int lch);
>> extern dma_addr_t omap_get_dma_dst_pos(int lch);
>> +extern void omap_set_dma_dst_pos(int lch, int value);
>> extern void omap_clear_dma(int lch);
>> extern int omap_get_dma_active_status(int lch);
>> extern int omap_dma_running(void);
>> --
> CDAC is not the destination address, as the API seems to suggest.
> CDSA (Channel Destination Start Address) is.
>
> CDAC is a running counter of the current transfer.
> I propose to update the omap_start_dma to reset CDAC to 0 always.
I agree with Venkat. I think having it reset for every transfer
by default is the right way to handle this.
Kevin
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Re: [PATCH v2] OMAP: DMA: Add API for setting channel dest addr
Manjunath,
On Tue, Mar 2, 2010 at 7:06 PM, Manjunatha GK wrote:
> The new API - omap_set_dma_dst_pos(int lch, int value) is added
> for setting channel destination address in CPC/CDAC register
>
> Cc: Tony Lindgren
> Cc: Santosh Shilimkar
> Cc: S, Venkatraman
> Signed-off-by: Manjunatha GK
> Signed-off-by: Govindraj R
> ---
> arch/arm/plat-omap/dma.c | 17 +
> arch/arm/plat-omap/include/plat/dma.h | 1 +
> 2 files changed, 18 insertions(+), 0 deletions(-)
>
> diff --git a/arch/arm/plat-omap/dma.c b/arch/arm/plat-omap/dma.c
> index 2ab224c..c73f11a 100644
> --- a/arch/arm/plat-omap/dma.c
> +++ b/arch/arm/plat-omap/dma.c
> @@ -1109,6 +1109,23 @@ dma_addr_t omap_get_dma_dst_pos(int lch)
> }
> EXPORT_SYMBOL(omap_get_dma_dst_pos);
>
> +/**
> + * omap_set_dma_dst_pos() - Set DMA channel destination address
> + * @arg1: lch DMA logical channel number
> + * @arg2: value Value to write into CDAC register
> + *
> + * Writes "value" into the register CPC/CDAC
> + */
> +void omap_set_dma_dst_pos(int lch, int value)
> +{
> + if (cpu_is_omap15xx())
> + dma_write(value, CPC(lch));
> + else
> + dma_write(value, CDAC(lch));
> +
> +}
> +EXPORT_SYMBOL(omap_set_dma_dst_pos);
> +
> int omap_get_dma_active_status(int lch)
> {
> return (dma_read(CCR(lch)) & OMAP_DMA_CCR_EN) != 0;
> diff --git a/arch/arm/plat-omap/include/plat/dma.h
> b/arch/arm/plat-omap/include/plat/dma.h
> index 02232ca..3b6e43e 100644
> --- a/arch/arm/plat-omap/include/plat/dma.h
> +++ b/arch/arm/plat-omap/include/plat/dma.h
> @@ -509,6 +509,7 @@ extern int omap_set_dma_callback(int lch,
> void *data);
> extern dma_addr_t omap_get_dma_src_pos(int lch);
> extern dma_addr_t omap_get_dma_dst_pos(int lch);
> +extern void omap_set_dma_dst_pos(int lch, int value);
> extern void omap_clear_dma(int lch);
> extern int omap_get_dma_active_status(int lch);
> extern int omap_dma_running(void);
> --
CDAC is not the destination address, as the API seems to suggest.
CDSA (Channel Destination Start Address) is.
CDAC is a running counter of the current transfer.
I propose to update the omap_start_dma to reset CDAC to 0 always.
Best regards,
Venkat.
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