From: Arnd Bergmann <arnd@arndb.de>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
smohanad@codeaurora.org, Jeffrey Hugo <jhugo@codeaurora.org>,
Kalle Valo <kvalo@codeaurora.org>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
hemantk@codeaurora.org,
linux-arm-msm <linux-arm-msm@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 02/16] bus: mhi: core: Add support for registering MHI controllers
Date: Mon, 17 Feb 2020 17:04:52 +0100 [thread overview]
Message-ID: <CAK8P3a28cZzOD7NfjBR=g6fADGgqwE7PFgOJrh6fph3QmDhKGQ@mail.gmail.com> (raw)
In-Reply-To: <20200217141503.GA1110972@kroah.com>
On Mon, Feb 17, 2020 at 3:15 PM Greg KH <gregkh@linuxfoundation.org> wrote:
> On Mon, Feb 17, 2020 at 06:34:19PM +0530, Manivannan Sadhasivam wrote:
> > On Mon, Feb 17, 2020 at 12:59:30PM +0100, Greg KH wrote:
> > ```
> > struct mhi_device *mhi_alloc_device(struct mhi_controller *mhi_cntrl)
> > {
> > ...
> > dev->parent = mhi_cntrl->dev;
> > ...
> > ```
> >
> > Hence, having the parent dev pointer really helps.
>
> Yes, saving the parent device is fine, but you should be doing your own
> dma calls using _your_ device, not the parents. Only mess with the
> parent pointer if you need to do something "normal" for a parent.
The MHI device is not involved in DMA at all, as it is not a DMA master,
and has no knowledge of the memory management or whether there
is any DMA at all. I think it is the right abstraction for an MHI driver to
pass kernel pointers into the subsystem interfaces, which then get
mapped by the bus driver that owns the DMA master.
This is similar to how e.g. USB drivers pass data into the USB core
interfaces, which then get the HCI driver to map/unmap it into the
DMA masters.
Arnd
next prev parent reply other threads:[~2020-02-17 16:05 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-31 13:49 [PATCH v2 00/16] Add MHI bus support Manivannan Sadhasivam
2020-01-31 13:49 ` [PATCH v2 01/16] docs: Add documentation for MHI bus Manivannan Sadhasivam
2020-01-31 22:57 ` Jeffrey Hugo
2020-01-31 13:49 ` [PATCH v2 02/16] bus: mhi: core: Add support for registering MHI controllers Manivannan Sadhasivam
2020-02-06 16:56 ` Greg KH
2020-02-11 19:11 ` Manivannan Sadhasivam
2020-02-11 19:22 ` Greg KH
2020-02-13 15:22 ` Manivannan Sadhasivam
2020-02-06 16:57 ` Greg KH
2020-02-11 18:41 ` Manivannan Sadhasivam
2020-02-11 19:20 ` Greg KH
2020-02-13 15:20 ` Manivannan Sadhasivam
2020-02-13 15:34 ` Greg KH
2020-02-13 15:48 ` Manivannan Sadhasivam
2020-02-13 15:53 ` Greg KH
2020-02-14 16:41 ` Jeffrey Hugo
2020-02-17 5:27 ` Manivannan Sadhasivam
2020-02-17 11:45 ` Greg KH
2020-02-17 11:53 ` Manivannan Sadhasivam
2020-02-17 11:59 ` Greg KH
2020-02-17 13:04 ` Manivannan Sadhasivam
2020-02-17 14:15 ` Greg KH
2020-02-17 16:04 ` Arnd Bergmann [this message]
2020-02-17 16:32 ` Greg KH
2020-02-17 17:50 ` Manivannan Sadhasivam
2020-02-06 17:08 ` Jeffrey Hugo
2020-01-31 13:49 ` [PATCH v2 03/16] bus: mhi: core: Add support for registering MHI client drivers Manivannan Sadhasivam
2020-01-31 23:00 ` Jeffrey Hugo
2020-01-31 13:49 ` [PATCH v2 04/16] bus: mhi: core: Add support for creating and destroying MHI devices Manivannan Sadhasivam
2020-02-06 16:16 ` Jeffrey Hugo
2020-01-31 13:49 ` [PATCH v2 05/16] bus: mhi: core: Add support for ringing channel/event ring doorbells Manivannan Sadhasivam
2020-02-06 20:14 ` Jeffrey Hugo
2020-01-31 13:49 ` [PATCH v2 06/16] bus: mhi: core: Add support for PM state transitions Manivannan Sadhasivam
2020-02-06 20:15 ` Jeffrey Hugo
2020-01-31 13:50 ` [PATCH v2 07/16] bus: mhi: core: Add support for basic PM operations Manivannan Sadhasivam
2020-02-06 20:15 ` Jeffrey Hugo
2020-01-31 13:50 ` [PATCH v2 08/16] bus: mhi: core: Add support for downloading firmware over BHIe Manivannan Sadhasivam
2020-02-06 20:15 ` Jeffrey Hugo
2020-01-31 13:50 ` [PATCH v2 09/16] bus: mhi: core: Add support for downloading RDDM image during panic Manivannan Sadhasivam
2020-02-06 16:41 ` Jeffrey Hugo
2020-02-06 20:17 ` Jeffrey Hugo
2020-01-31 13:50 ` [PATCH v2 10/16] bus: mhi: core: Add support for processing events from client device Manivannan Sadhasivam
2020-02-06 20:16 ` Jeffrey Hugo
2020-01-31 13:50 ` [PATCH v2 11/16] bus: mhi: core: Add support for data transfer Manivannan Sadhasivam
2020-02-06 20:16 ` Jeffrey Hugo
2020-02-17 16:13 ` Arnd Bergmann
2020-02-17 16:47 ` Manivannan Sadhasivam
2020-02-18 5:51 ` Manivannan Sadhasivam
2020-02-18 14:34 ` Arnd Bergmann
2020-01-31 13:50 ` [PATCH v2 12/16] bus: mhi: core: Add uevent support for module autoloading Manivannan Sadhasivam
2020-02-06 20:16 ` Jeffrey Hugo
2020-01-31 13:50 ` [PATCH v2 13/16] MAINTAINERS: Add entry for MHI bus Manivannan Sadhasivam
2020-02-03 10:16 ` Andy Shevchenko
2020-02-04 7:05 ` Manivannan Sadhasivam
2020-01-31 13:50 ` [PATCH v2 14/16] net: qrtr: Add MHI transport layer Manivannan Sadhasivam
2020-02-03 18:12 ` Jakub Kicinski
2020-02-04 8:19 ` Manivannan Sadhasivam
2020-02-07 0:14 ` Chris Lew
2020-02-11 3:50 ` Manivannan Sadhasivam
2020-02-12 1:01 ` Chris Lew
2020-01-31 13:50 ` [PATCH v2 15/16] net: qrtr: Do not depend on ARCH_QCOM Manivannan Sadhasivam
2020-01-31 13:50 ` [PATCH v2 16/16] soc: qcom: Do not depend on ARCH_QCOM for QMI helpers Manivannan Sadhasivam
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