[PATCH 1/3] dmaengine: pl330: Set residue in tx_status callback.

[Dylan Reid]

On Thu, Sep 12, 2013 at 4:40 AM, Chanho Park <chanho61.park at samsung.com> wrote:
> Hi Padmavathi,
>
>> -----Original Message-----
>> From: linux-arm-kernel [mailto:linux-arm-kernel-
>> bounces at lists.infradead.org] On Behalf Of Padmavathi Venna
>> Sent: Wednesday, September 11, 2013 3:08 PM
>> To: linux-samsung-soc at vger.kernel.org; linux-arm-
>> kernel at lists.infradead.org; padma.v at samsung.com; padma.kvr at gmail.com
>> Cc: kgene.kim at samsung.com; arnd at arndb.de; sbkim73 at samsung.com;
>> vinod.koul at intel.com; broonie at kernel.org; dgreid at chromium.org;
>> olofj at chromium.org
>> Subject: [PATCH 1/3] dmaengine: pl330: Set residue in tx_status callback.
>>
>> From: Dylan Reid <dgreid at chromium.org>
>>
>> Fill txstate.residue with the amount of bytes remaining in the current
>> transfer if the transfer is not complete.  This will be of particular use
>> to i2s DMA transfers, providing more accurate hw_ptr values to ASoC.
>>
>> Signed-off-by: Dylan Reid <dgreid at chromium.org>
>> Reviewed-by: Olof Johansson <olofj at chromium.org>
>> Signed-off-by: Padmavathi Venna <padma.v at samsung.com>
>> ---
>>  drivers/dma/pl330.c |   55
>> ++++++++++++++++++++++++++++++++++++++++++++++++++-
>>  1 files changed, 54 insertions(+), 1 deletions(-)
>>
>> diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c index
>> 593827b..7ab9136 100644
>> --- a/drivers/dma/pl330.c
>> +++ b/drivers/dma/pl330.c
>> @@ -2476,11 +2476,64 @@ static void pl330_free_chan_resources(struct
>> dma_chan *chan)
>>       spin_unlock_irqrestore(&pch->lock, flags);  }
>>
>> +static inline int
>> +pl330_src_addr_in_desc(struct dma_pl330_desc *desc, unsigned int sar) {
>> +     return ((desc->px.src_addr <= sar) &&
>> +             (sar <= (desc->px.src_addr + desc->px.bytes))); }
>> +
>> +static inline int
>> +pl330_dst_addr_in_desc(struct dma_pl330_desc *desc, unsigned int dar) {
>> +     return ((desc->px.dst_addr <= dar) &&
>> +             (dar <= (desc->px.dst_addr + desc->px.bytes))); }
>> +
>> +static unsigned int pl330_tx_residue(struct dma_chan *chan) {
>> +     struct dma_pl330_chan *pch = to_pchan(chan);
>> +     void __iomem *regs = pch->dmac->pif.base;
>> +     struct pl330_thread *thrd = pch->pl330_chid;
>> +     struct dma_pl330_desc *desc;
>> +     unsigned int sar, dar;
>> +     unsigned int residue = 0;
>> +     unsigned long flags;
>> +
>> +     sar = readl(regs + SA(thrd->id));
>> +     dar = readl(regs + DA(thrd->id));
>> +
>> +     spin_lock_irqsave(&pch->lock, flags);
>> +
>> +     /* Find the desc related to the current buffer. */
>> +     list_for_each_entry(desc, &pch->work_list, node) {
>> +             if (desc->rqcfg.src_inc && pl330_src_addr_in_desc(desc,
>> sar)) {
>> +                     residue = desc->px.bytes - (sar -
> desc->px.src_addr);
>> +                     goto found_unlock;
>> +             }
>> +             if (desc->rqcfg.dst_inc && pl330_dst_addr_in_desc(desc,
>> dar)) {
>> +                     residue = desc->px.bytes - (dar -
> desc->px.dst_addr);
>> +                     goto found_unlock;
>> +             }
>> +     }
>> +
>> +found_unlock:
>> +     spin_unlock_irqrestore(&pch->lock, flags);
>> +
>> +     return residue;
>> +}
>> +
>>  static enum dma_status
>>  pl330_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
>>                struct dma_tx_state *txstate)
>>  {
>> -     return dma_cookie_status(chan, cookie, txstate);
>> +     enum dma_status ret;
>> +
>> +     ret = dma_cookie_status(chan, cookie, txstate);
>> +     if (ret != DMA_SUCCESS) /* Not complete, check amount left. */
>> +             dma_set_residue(txstate, pl330_tx_residue(chan));
>> +
>> +     return ret;
>
> Why didn't you use a cookie value to track the request?
> The cookie is assigned when each transfer is submitted.
> If you save the value in the desc, we can find the request easily.

If there are several cyclic desc in the work list, is there a better
way to find the "current" one?  The chan struct tracks the last
completed and last submitted cookies, but these will be the first and
last respectively as long as the cyclic transfer is active.  Is there
an "active" cookie stored somewhere that I missed?

Looking for the first buffer with status == BUSY is an improvement
I'll make.  Any way to avoid looking through the list?

Thanks,

Dylan

>
> Thanks,
>
> Best  Regards,
> Chanho Park
>