From: Robin Murphy <robin.murphy@arm.com>
To: srinivas.kandagatla@linaro.org, will.deacon@arm.com,
bjorn.andersson@linaro.org
Cc: joro@8bytes.org, ohad@wizery.com,
linux-arm-kernel@lists.infradead.org,
iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
linux-remoteproc@vger.kernel.org
Subject: Re: [PATCH 2/3] rpmsg: core: make rpmsg bus DMA capable
Date: Fri, 2 Mar 2018 16:14:44 +0000 [thread overview]
Message-ID: <07503032-b08b-10ea-9d34-ddf85c682a9d@arm.com> (raw)
In-Reply-To: <20180302145531.20463-3-srinivas.kandagatla@linaro.org>
On 02/03/18 14:55, srinivas.kandagatla@linaro.org wrote:
> From: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
>
> Many of the rpmsg clients like audio drivers need to allocate
> dma memory. Make this bus DMA capable so that the child devices
> can use dma apis.
AFAICS after 15 minutes in the docs and code, the rpmsg "bus" is a
virtual one based around shared-memory mailbox communication, so I don't
really see how DMA exists in that context - I think maybe that
abstraction needs looking at.
However, from grepping through the DTs it seems at first glance like the
non-trivial things under the "qcom,smd" bus mostly map to actual
platform devices via the "qcom,smd-edge" property - if those platform
devices are the physical DMA masters, they should be the ones used for
DMA API operations.
> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
> ---
> drivers/rpmsg/rpmsg_core.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
> index e84c71f8d6ab..540a3f3567b8 100644
> --- a/drivers/rpmsg/rpmsg_core.c
> +++ b/drivers/rpmsg/rpmsg_core.c
> @@ -472,6 +472,7 @@ struct bus_type rpmsg_bus = {
> .uevent = rpmsg_uevent,
> .probe = rpmsg_dev_probe,
> .remove = rpmsg_dev_remove,
> + .force_dma = true,
Regardless of the above, would you really need to use this brute force
hack instead of just fixing the DTs? I'm struggling to find which
drivers might currently be relying on this :/
Robin.
> };
> EXPORT_SYMBOL(rpmsg_bus);
>
>
WARNING: multiple messages have this Message-ID (diff)
From: Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>
To: srinivas.kandagatla-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org,
will.deacon-5wv7dgnIgG8@public.gmane.org,
bjorn.andersson-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org
Cc: ohad-Ix1uc/W3ht7QT0dZR+AlfA@public.gmane.org,
linux-remoteproc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
Subject: Re: [PATCH 2/3] rpmsg: core: make rpmsg bus DMA capable
Date: Fri, 2 Mar 2018 16:14:44 +0000 [thread overview]
Message-ID: <07503032-b08b-10ea-9d34-ddf85c682a9d@arm.com> (raw)
In-Reply-To: <20180302145531.20463-3-srinivas.kandagatla-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
On 02/03/18 14:55, srinivas.kandagatla-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org wrote:
> From: Srinivas Kandagatla <srinivas.kandagatla-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
>
> Many of the rpmsg clients like audio drivers need to allocate
> dma memory. Make this bus DMA capable so that the child devices
> can use dma apis.
AFAICS after 15 minutes in the docs and code, the rpmsg "bus" is a
virtual one based around shared-memory mailbox communication, so I don't
really see how DMA exists in that context - I think maybe that
abstraction needs looking at.
However, from grepping through the DTs it seems at first glance like the
non-trivial things under the "qcom,smd" bus mostly map to actual
platform devices via the "qcom,smd-edge" property - if those platform
devices are the physical DMA masters, they should be the ones used for
DMA API operations.
> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> ---
> drivers/rpmsg/rpmsg_core.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
> index e84c71f8d6ab..540a3f3567b8 100644
> --- a/drivers/rpmsg/rpmsg_core.c
> +++ b/drivers/rpmsg/rpmsg_core.c
> @@ -472,6 +472,7 @@ struct bus_type rpmsg_bus = {
> .uevent = rpmsg_uevent,
> .probe = rpmsg_dev_probe,
> .remove = rpmsg_dev_remove,
> + .force_dma = true,
Regardless of the above, would you really need to use this brute force
hack instead of just fixing the DTs? I'm struggling to find which
drivers might currently be relying on this :/
Robin.
> };
> EXPORT_SYMBOL(rpmsg_bus);
>
>
WARNING: multiple messages have this Message-ID (diff)
From: robin.murphy@arm.com (Robin Murphy)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/3] rpmsg: core: make rpmsg bus DMA capable
Date: Fri, 2 Mar 2018 16:14:44 +0000 [thread overview]
Message-ID: <07503032-b08b-10ea-9d34-ddf85c682a9d@arm.com> (raw)
In-Reply-To: <20180302145531.20463-3-srinivas.kandagatla@linaro.org>
On 02/03/18 14:55, srinivas.kandagatla at linaro.org wrote:
> From: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
>
> Many of the rpmsg clients like audio drivers need to allocate
> dma memory. Make this bus DMA capable so that the child devices
> can use dma apis.
AFAICS after 15 minutes in the docs and code, the rpmsg "bus" is a
virtual one based around shared-memory mailbox communication, so I don't
really see how DMA exists in that context - I think maybe that
abstraction needs looking at.
However, from grepping through the DTs it seems at first glance like the
non-trivial things under the "qcom,smd" bus mostly map to actual
platform devices via the "qcom,smd-edge" property - if those platform
devices are the physical DMA masters, they should be the ones used for
DMA API operations.
> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
> ---
> drivers/rpmsg/rpmsg_core.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
> index e84c71f8d6ab..540a3f3567b8 100644
> --- a/drivers/rpmsg/rpmsg_core.c
> +++ b/drivers/rpmsg/rpmsg_core.c
> @@ -472,6 +472,7 @@ struct bus_type rpmsg_bus = {
> .uevent = rpmsg_uevent,
> .probe = rpmsg_dev_probe,
> .remove = rpmsg_dev_remove,
> + .force_dma = true,
Regardless of the above, would you really need to use this brute force
hack instead of just fixing the DTs? I'm struggling to find which
drivers might currently be relying on this :/
Robin.
> };
> EXPORT_SYMBOL(rpmsg_bus);
>
>
next prev parent reply other threads:[~2018-03-02 16:14 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-02 14:55 [PATCH 0/3] drivers: rpmsg: make rpmsg bus DMA capable srinivas.kandagatla
2018-03-02 14:55 ` srinivas.kandagatla at linaro.org
2018-03-02 14:55 ` srinivas.kandagatla-QSEj5FYQhm4dnm+yROfE0A
2018-03-02 14:55 ` [PATCH 1/3] rpmsg: core: export rpmsg bus type srinivas.kandagatla
2018-03-02 14:55 ` srinivas.kandagatla at linaro.org
2018-03-02 14:55 ` srinivas.kandagatla-QSEj5FYQhm4dnm+yROfE0A
2018-03-02 15:25 ` Robin Murphy
2018-03-02 15:25 ` Robin Murphy
2018-03-02 15:25 ` Robin Murphy
2018-03-02 14:55 ` [PATCH 2/3] rpmsg: core: make rpmsg bus DMA capable srinivas.kandagatla
2018-03-02 14:55 ` srinivas.kandagatla at linaro.org
2018-03-02 14:55 ` srinivas.kandagatla-QSEj5FYQhm4dnm+yROfE0A
2018-03-02 16:14 ` Robin Murphy [this message]
2018-03-02 16:14 ` Robin Murphy
2018-03-02 16:14 ` Robin Murphy
2018-03-02 16:40 ` Srinivas Kandagatla
2018-03-02 16:40 ` Srinivas Kandagatla
2018-03-18 22:47 ` Bjorn Andersson
2018-03-18 22:47 ` Bjorn Andersson
2018-03-18 22:47 ` Bjorn Andersson
2018-03-02 14:55 ` [PATCH 3/3] iommu: armsmmu: set iommu ops for rpmsg bus srinivas.kandagatla
2018-03-02 14:55 ` srinivas.kandagatla at linaro.org
2018-03-02 14:55 ` srinivas.kandagatla-QSEj5FYQhm4dnm+yROfE0A
2018-03-02 16:59 ` Robin Murphy
2018-03-02 16:59 ` Robin Murphy
2018-03-02 16:59 ` Robin Murphy
2018-05-07 19:28 ` Bjorn Andersson
2018-05-07 19:28 ` Bjorn Andersson
2018-05-07 19:28 ` Bjorn Andersson
2018-05-11 18:24 ` Robin Murphy
2018-05-11 18:24 ` Robin Murphy
2018-05-11 18:24 ` Robin Murphy
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