Re: [PATCH v6 2/2] i2c: i2c-qcom-geni: Add Block event interrupt support
From: Jyothi Kumar Seerapu
Date: Fri Jul 25 2025 - 06:50:53 EST
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.