Re: [PATCH v7 05/11] dmaengine: Introduce DMA-device device_caps callback
From: Dave Jiang
Date: Tue Jul 14 2020 - 12:18:20 EST
On 7/14/2020 9:08 AM, Vinod Koul wrote:
On 13-07-20, 13:55, Dave Jiang wrote:
On 7/10/2020 2:38 AM, Serge Semin wrote:
On Fri, Jul 10, 2020 at 11:45:03AM +0300, Andy Shevchenko wrote:
On Fri, Jul 10, 2020 at 01:45:44AM +0300, Serge Semin wrote:
There are DMA devices (like ours version of Synopsys DW DMAC) which have
DMA capabilities non-uniformly redistributed between the device channels.
In order to provide a way of exposing the channel-specific parameters to
the DMA engine consumers, we introduce a new DMA-device callback. In case
if provided it gets called from the dma_get_slave_caps() method and is
able to override the generic DMA-device capabilities.
In light of recent developments consider not to add 'slave' and a such words to the kernel.
As long as the 'slave' word is used in the name of the dma_slave_caps
structure and in the rest of the DMA-engine subsystem, it will be ambiguous
to use some else terminology. If renaming needs to be done, then it should be
done synchronously for the whole subsystem.
What about just calling it dma_device_caps? Consider this is a useful
function not only slave DMA will utilize this. I can see this being useful
for some of my future code with idxd driver.
Some of the caps may make sense to generic dmaengine but few of them do
not :) While at it, am planning to make it dmaengine_periph_caps to
denote that these are dmaengine peripheral capabilities.
If the function only passes in periph_caps, how do we allow the non periph DMA
utilize this function?