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Date:	Wed, 26 Sep 2012 09:47:48 +0300
From:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:	viresh kumar <viresh.kumar@...aro.org>
Cc:	Vinod Koul <vinod.koul@...el.com>, linux-kernel@...r.kernel.org,
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Subject: Re: [PATCHv1 2/6] dmaengine: dw_dmac: add driver for Atmel AT32

On Wed, 2012-09-26 at 09:20 +0530, viresh kumar wrote: 
> On Tue, Sep 25, 2012 at 5:43 PM, Andy Shevchenko
> <andriy.shevchenko@...ux.intel.com> wrote:
> > From: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> >
> > This driver should be usable on all platforms that depend on clk API.
> 
> This is not what you mentioned in subject :(

> 
> > Signed-off-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> > Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> > ---
> >  drivers/dma/Kconfig        |    9 +++
> >  drivers/dma/Makefile       |    1 +
> >  drivers/dma/dw_dmac.c      |   23 +------
> >  drivers/dma/dw_dmac_at32.c |  150 ++++++++++++++++++++++++++++++++++++++++++++
> 
> I don't agree with the naming used here. There is nothing AT32
> specific here. It is actively used
> by SPEAr. It should be named dw_dmac_platform.c or *pltfm.c

This separate driver makes no sense in case it is built properly without
CLK framework. Let me check this and leave comments at patch 1/6.

> 
> >  4 files changed, 162 insertions(+), 21 deletions(-)
> >  create mode 100644 drivers/dma/dw_dmac_at32.c
> >
> > diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
> > index df32537..e47cc90 100644
> > --- a/drivers/dma/Kconfig
> > +++ b/drivers/dma/Kconfig
> > @@ -89,6 +89,15 @@ config DW_DMAC
> >           Support the Synopsys DesignWare AHB DMA controller.  This
> >           can be integrated in chips such as the Atmel AT32ap7000.
> >
> > +config DW_DMAC_AT32
> > +       tristate "Synopsys DesignWare AHB DMA support for Atmel"
> 
> :(
> 
> > +       depends on HAVE_CLK
> 
> Even this is not a must for all users of platform driver. So can leave this.
> 
> > +       select DW_DMAC
> > +       default y if CPU_AT32AP7000
> > +       help
> > +         Support the Synopsys DesignWare AHB DMA controller in the chips
> > +         such as the Atmel AT32ap7000.
> > +
> >  config AT_HDMAC
> >         tristate "Atmel AHB DMA support"
> >         depends on ARCH_AT91
> 
> > diff --git a/drivers/dma/dw_dmac.c b/drivers/dma/dw_dmac.c
> > index d9344a7..9c8a500 100644
> > --- a/drivers/dma/dw_dmac.c
> > +++ b/drivers/dma/dw_dmac.c
> > @@ -18,7 +18,6 @@
> >  #include <linux/init.h>
> >  #include <linux/interrupt.h>
> >  #include <linux/io.h>
> > -#include <linux/of.h>
> >  #include <linux/mm.h>
> >  #include <linux/module.h>
> >  #include <linux/platform_device.h>
> > @@ -1681,35 +1680,17 @@ static const struct dev_pm_ops dw_dev_pm_ops = {
> >         .poweroff_noirq = dw_suspend_noirq,
> >  };
> >
> > -#ifdef CONFIG_OF
> > -static const struct of_device_id dw_dma_id_table[] = {
> > -       { .compatible = "snps,dma-spear1340" },
> > -       {}
> > -};
> > -MODULE_DEVICE_TABLE(of, dw_dma_id_table);
> > -#endif
> > -
> >  static struct platform_driver dw_driver = {
> > +       .probe          = dw_probe,
> >         .remove         = __devexit_p(dw_remove),
> >         .shutdown       = dw_shutdown,
> >         .driver = {
> >                 .name   = "dw_dmac",
> >                 .pm     = &dw_dev_pm_ops,
> > -               .of_match_table = of_match_ptr(dw_dma_id_table),
> >         },
> >  };
> >
> > -static int __init dw_init(void)
> > -{
> > -       return platform_driver_probe(&dw_driver, dw_probe);
> > -}
> > -subsys_initcall(dw_init);
> > -
> > -static void __exit dw_exit(void)
> > -{
> > -       platform_driver_unregister(&dw_driver);
> > -}
> > -module_exit(dw_exit);
> > +module_platform_driver(dw_driver);
> 
> Shouldn't this be a separate patch?
> 
> >
> >  MODULE_LICENSE("GPL v2");
> >  MODULE_DESCRIPTION("Synopsys DesignWare DMA Controller driver");
> > diff --git a/drivers/dma/dw_dmac_at32.c b/drivers/dma/dw_dmac_at32.c
> > new file mode 100644
> > index 0000000..7bc7ac4
> > --- /dev/null
> > +++ b/drivers/dma/dw_dmac_at32.c
> > @@ -0,0 +1,150 @@
> > +/*
> > + * Driver for the Synopsys DesignWare DMA Controller
> 
> How is this file different from dw_dmac.c?
> 
> > + *
> > + * The driver is based on the excerpts from the original dw_dmac.c. That's why
> > + * the same copyright holders are mentioned here as well.
> > + *
> > + * Copyright (C) 2007-2008 Atmel Corporation
> > + * Copyright (C) 2010-2011 ST Microelectronics
> > + * Copyright (C) 2012 Intel Corporation
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License version 2 as
> > + * published by the Free Software Foundation.
> > + */
> > +#include <linux/module.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/slab.h>
> > +#include <linux/clk.h>
> > +#include <linux/of.h>
> > +#include <linux/dw_dmac.h>
> > +
> > +struct dw_at32 {
> > +       struct platform_device  *pdev;
> > +       struct clk              *clk;
> > +};
> > +
> > +static int __init dw_at32_probe(struct platform_device *pdev)
> > +{
> > +       struct dw_at32                  *at32;
> > +       struct platform_device          *pd;
> > +       struct dw_dma_platform_data     *pdata = pdev->dev.platform_data;
> > +       static int                      instance;
> > +       int                             ret;
> > +
> > +       at32 = devm_kzalloc(&pdev->dev, sizeof(*at32), GFP_KERNEL);
> > +       if (!at32) {
> > +               dev_err(&pdev->dev, "can't allocate memory\n");
> > +               return -ENOMEM;
> > +       }
> > +
> > +       pd = platform_device_alloc("dw_dmac", instance);
> > +       if (!pd) {
> > +               dev_err(&pdev->dev, "can't allocate dw_dmac platform device\n");
> > +               return -ENOMEM;
> > +       }
> 
> Why create another device? Why not simply call dw_probe() from here?

-- 
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Intel Finland Oy
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