linux-kernel - Re: [PATCH V5 0/2] Change vring space from nomal memory to dma coherent memory

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Date:   Wed, 28 Oct 2020 06:58:36 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Sherry Sun <sherry.sun@....com>
Cc:     hch@...radead.org, vincent.whitchurch@...s.com,
        sudeep.dutt@...el.com, ashutosh.dixit@...el.com, arnd@...db.de,
        kishon@...com, lorenzo.pieralisi@....com,
        linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
        linux-imx@....com, fugang.duan@....com
Subject: Re: [PATCH V5 0/2] Change vring space from nomal memory to dma
 coherent memory

On Wed, Oct 28, 2020 at 10:03:03AM +0800, Sherry Sun wrote:
> Changes in V5:
> 1. Reorganize the vop_mmap function code in patch 1, which is done by Christoph. 
> 2. Completely remove the unnecessary code related to reassign the used ring for
> card in patch 2.
> 
> The original vop driver only supports dma coherent device, as it allocates and
> maps vring by _get_free_pages and dma_map_single, but not use 
> dma_sync_single_for_cpu/device to sync the updates of device_page/vring between
> EP and RC, which will cause memory synchronization problem for device don't
> support hardware dma coherent.
> 
> And allocate vrings use dma_alloc_coherent is a common way in kernel, as the
> memory interacted between two systems should use consistent memory to avoid
> caching effects. So here add noncoherent platform support for vop driver.
> Also add some related dma changes to make sure noncoherent platform works
> well.
> 
> Sherry Sun (2):
>   misc: vop: change the way of allocating vrings and device page
>   misc: vop: do not allocate and reassign the used ring
> 
>  drivers/misc/mic/bus/vop_bus.h     |   2 +
>  drivers/misc/mic/host/mic_boot.c   |   9 ++
>  drivers/misc/mic/host/mic_main.c   |  43 ++------
>  drivers/misc/mic/vop/vop_debugfs.c |   4 -
>  drivers/misc/mic/vop/vop_main.c    |  70 +-----------
>  drivers/misc/mic/vop/vop_vringh.c  | 166 ++++++++++-------------------
>  include/uapi/linux/mic_common.h    |   9 +-
>  7 files changed, 85 insertions(+), 218 deletions(-)

Have you all seen:
	https://lore.kernel.org/r/8c1443136563de34699d2c084df478181c205db4.1603854416.git.sudeep.dutt@intel.com

Looks like this code is asking to just be deleted, is that ok with you?

thanks,

greg k-h