Re: [PATCH v6 2/2] i2c: i2c-qcom-geni: Add Block event interrupt support

[Vinod Koul <vkoul@kernel.org>]

On 25-07-25, 16:20, Jyothi Kumar Seerapu wrote:
> 
> 
> On 7/23/2025 12:45 PM, Vinod Koul wrote:
> > On 22-07-25, 15:46, Dmitry Baryshkov wrote:
> > > On Tue, Jul 22, 2025 at 05:50:08PM +0530, Jyothi Kumar Seerapu wrote:
> > > > On 7/19/2025 3:27 PM, Dmitry Baryshkov wrote:
> > > > > On Mon, Jul 07, 2025 at 09:58:30PM +0530, Jyothi Kumar Seerapu wrote:
> > > > > > On 7/4/2025 1:11 AM, Dmitry Baryshkov wrote:
> > > > > > > On Thu, 3 Jul 2025 at 15:51, Jyothi Kumar Seerapu
> > 
> > [Folks, would be nice to trim replies]
> > 
> > > > > > Could you please confirm if can go with the similar approach of unmap the
> > > > > > processed TREs based on a fixed threshold or constant value, instead of
> > > > > > unmapping them all at once?
> > > > > 
> > > > > I'd still say, that's a bad idea. Please stay within the boundaries of
> > > > > the DMA API.
> > > > > 
> > > > I agree with the approach you suggested—it's the GPI's responsibility to
> > > > manage the available TREs.
> > > > 
> > > > However, I'm curious whether can we set a dynamic watermark value perhaps
> > > > half the available TREs) to trigger unmapping of processed TREs ? This would
> > > > allow the software to prepare the next set of TREs while the hardware
> > > > continues processing the remaining ones, enabling better parallelism and
> > > > throughput.
> > > 
> > > Let's land the simple implementation first, which can then be improved.
> > > However I don't see any way to return 'above the watermark' from the DMA
> > > controller. You might need to enhance the API.
> > 
> > Traditionally, we set the dma transfers for watermark level and we get a
> > interrupt. So you might want to set the callback for watermark level
> > and then do mapping/unmapping etc in the callback. This is typical model
> > for dmaengines, we should follow that well
> > 
> > BR
> 
> Thanks Dmitry and Vinod, I will work on V7 patch for submitting the I2C
> messages until they fit and and unmap all processed messages together for
> now.
> 
> Regarding the watermark mechanism, looks GENI SE DMA supports watermark
> interrupts but it appears that GPI DMA doesn't have such provision of
> watermark.

What is the mechanism to get interrupts from the GPI? If you submit 10
txn, can you ask it to interrupt when half of them are done?

-- 
~Vinod