Re: [PATCH 4/6] zram: Add QPaCE zcomp backend

[Oreoluwa Babatunde]

On 10/1/2026 1:51 AM, Krzysztof Kozlowski wrote:
> On Wed, Sep 30, 2026 at 07:52:13AM -0700, Georgi Djakov wrote:
> > Add a zcomp backend for the Qualcomm Page Compression Engine (QPaCE) so
> > zram can expose qpace-lz4 as a selectable compression algorithm when the
> > QPaCE driver is available.
> >
> > Compress and decompress operations are handled via the QPaCE urgent
> > synchronous path: each request DMA-maps the source and destination
> > buffers, issues a blocking hardware command, and returns the result size.
> >
> > Signed-off-by: Georgi Djakov <georgi.djakov@xxxxxxxxxxxxxxxx>
> > ---
> >   drivers/block/zram/Kconfig         |  11 +++
> >   drivers/block/zram/Makefile        |   1 +
> >   drivers/block/zram/backend_qpace.c | 134 +++++++++++++++++++++++++++++
>
> So entire qpace should go here, no? Why did you create this entire layer
> of indirection, singleton management under drivers/soc?

Since the qpace driver is not specific to zram and may be utilized by 
other kernel components, it should remain independent of drivers/zram.
Consolidating everything under drivers/zram would couple the 
implementation to a single use case and reduce its reusability.

The backend_qpace implementation was intended to setup zram as a user of 
qpace and follow the structure of the zcomp frameowork. As per your 
comment in the other patches, we will check if this can be done through 
the crypto framework.

> >   drivers/block/zram/backend_qpace.h |  13 +++
> >   drivers/block/zram/zcomp.c         |  11 ++-
> >   5 files changed, 168 insertions(+), 2 deletions(-)
> >   create mode 100644 drivers/block/zram/backend_qpace.c
> >   create mode 100644 drivers/block/zram/backend_qpace.h

Thanks,
Oreoluwa