linux-kernel - Re: [PATCH] staging: android: ion: refactory ion

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Date:   Sat, 30 Mar 2019 07:56:34 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     "Zengtao (B)" <prime.zeng@...ilicon.com>
Cc:     "devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>,
        Todd Kjos <tkjos@...roid.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linaro-mm-sig@...ts.linaro.org" <linaro-mm-sig@...ts.linaro.org>,
        Arve Hjønnevåg <arve@...roid.com>,
        Joel Fernandes <joel@...lfernandes.org>,
        Martijn Coenen <maco@...roid.com>,
        "sumit.semwal@...aro.org" <sumit.semwal@...aro.org>,
        Christian Brauner <christian@...uner.io>
Subject: Re: [PATCH] staging: android: ion: refactory ion_alloc for kernel
 driver use

On Sat, Mar 30, 2019 at 02:32:35AM +0000, Zengtao (B) wrote:
> >-----Original Message-----
> >From: Greg Kroah-Hartman [mailto:gregkh@...uxfoundation.org]
> >Sent: Saturday, March 30, 2019 12:04 AM
> >To: Zengtao (B) <prime.zeng@...ilicon.com>
> >Cc: labbott@...hat.com; sumit.semwal@...aro.org;
> >devel@...verdev.osuosl.org; Todd Kjos <tkjos@...roid.com>;
> >linux-kernel@...r.kernel.org; dri-devel@...ts.freedesktop.org;
> >linaro-mm-sig@...ts.linaro.org; Arve Hjønnevåg <arve@...roid.com>;
> >Joel Fernandes <joel@...lfernandes.org>; Martijn Coenen
> ><maco@...roid.com>; Christian Brauner <christian@...uner.io>
> >Subject: Re: [PATCH] staging: android: ion: refactory ion_alloc for kernel
> >driver use
> >
> >On Sat, Mar 30, 2019 at 02:40:16AM +0800, Zeng Tao wrote:
> >> There are two reasons for this patch:
> >> 1. There are some potential requirements for ion_alloc in kernel
> >> space, some media drivers need to allocate media buffers from ion
> >> instead of buddy or dma framework, this is more convient and clean
> >> very for media drivers. And In that case, ion is the only media buffer
> >> provider, it's more easier to maintain.
> >
> >As this really is just DMA, what is wrong with the existing dma framework
> >that makes it hard to use?  You have seen all of the changes recently to it,
> >right?
> 
> The current dma framework is powerful enough(to me, and more complex ^_^)
> , CMA, IOMMU are all integrated, it's good. But buffer sharing, statistics, debug,
>  are not so friendly for media drivers(each driver has to do all, but duplicate jobs).

Then go add statistics and debugging to the dma code so that everyone
benefits!

thanks,

greg k-h