Re: [PATCH v5 04/10] drivers: qcom: rpmh: add RPMH helper functions

[Lina Iyer]

On Tue, Apr 10 2018 at 20:23 -0600, Stephen Boyd wrote:
> Quoting Lina Iyer (2018-04-09 08:36:31)
> > On Fri, Apr 06 2018 at 19:21 -0600, Stephen Boyd wrote:
> > >Quoting Lina Iyer (2018-04-05 09:18:28)
> > >> diff --git a/include/soc/qcom/rpmh.h b/include/soc/qcom/rpmh.h
> > >> new file mode 100644
> > >> index 000000000000..95334d4c1ede
> > >> --- /dev/null
> > >> +++ b/include/soc/qcom/rpmh.h
> > >> @@ -0,0 +1,34 @@
> > >> +/* SPDX-License-Identifier: GPL-2.0 */
> > >> +/*
> > >> + * Copyright (c) 2016-2018, The Linux Foundation. All rights reserved.
> > >> + */
> > >> +
> > >> +#ifndef __SOC_QCOM_RPMH_H__
> > >> +#define __SOC_QCOM_RPMH_H__
> > >> +
> > >> +#include <soc/qcom/tcs.h>
> > >> +#include <linux/platform_device.h>
> > >> +
> > >> +struct rpmh_client;
> > >> +
> > >> +#if IS_ENABLED(CONFIG_QCOM_RPMH)
> > >> +int rpmh_write(struct rpmh_client *rc, enum rpmh_state state,
> > >> +              const struct tcs_cmd *cmd, u32 n);
> > >> +
> > >> +struct rpmh_client *rpmh_get_client(struct platform_device *pdev);
> > >> +
> > >> +void rpmh_release(struct rpmh_client *rc);
> > >
> > >Please get rid of this 'client' layer and fold it into the rpmh driver.
> > >Everything that uses the rpmh_client is a child device of the rpmh
> > >device so they should be able to just pass in their device pointer as
> > >their 'handle' and have the rpmh driver take that, get the parent device
> > >pointer, and pull an rpmh_drv structure out of there. The 'common' code
> > >can go into the base rpmh driver and get used from there and then we
> > >don't have to hop between two files to see how rpmh is used by the
> > >consumers. Code complexity goes down this way.
> >
> > That would be not be a good idea. This layer is not just providing an
> > API interface. There is resource buffering, handling of memory for
> > requests and downstream quirks and debug going on in this layer. It
> > would be unwise to clobber the hardware centric rpmh-rsc layer. If you
> > look at the series as a whole, you would understand why this is
> > necessary. I plan to build more on top of these patches in the future as
> > we add support for system low power modes. The complexity doesn't go
> > away, it just thrown in to another file, which is already decently
> > sized.
> >
> > I could try to use the device as a handle, and internally work on
> > getting the drv and other information from it, if that helps. But I do
> > not want to clobber these two files together. It doesn't help
> > maintainability.
>
> Using the device as a handle is a good start. Let's see how it looks
> once that part of the code gets replaced. I still fail to see how buffer
> management and requests are any different from poking the hardware, but
> OK. Maybe if this was a TCS "library" on top of the rpmh hardware
> interface?
This is essentially a TCS library.

-- Lina