Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: [PATCHv2 2/4] dmaengine: dw_dmac: Add PCI part of the driver | Date | Wed, 26 Sep 2012 19:41:11 +0000 |
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On Wednesday 26 September 2012, Andy Shevchenko wrote: > On Wed, Sep 26, 2012 at 5:33 PM, viresh kumar <viresh.kumar@linaro.org> wrote: > > On Wed, Sep 26, 2012 at 6:10 PM, Andy Shevchenko > > <andriy.shevchenko@linux.intel.com> wrote: > >> diff --git a/drivers/dma/dw_dmac_pci.c b/drivers/dma/dw_dmac_pci.c > >> +#include <linux/module.h> > >> +#include <linux/pci.h> > >> +#include <linux/platform_device.h> > >> +#include <linux/dw_dmac.h> > >> + > >> +#define DRIVER(_is_private, _chan_order, _chan_pri) \ > >> + ((kernel_ulong_t)&(struct dw_dma_platform_data) { \ > >> + .is_private = (_is_private), \ > >> + .chan_allocation_order = (_chan_order), \ > >> + .chan_priority = (_chan_pri), \ > > > > I believe you don't need these braces around input variables on right side > > of "=". Even if there is something complex passed. > Hmm... Have no idea if anyone will use robust stuff as a parameter to > that macro. I could remove them.
IMHO It's better to leave them in as general practice in case of a macro.
However, I would prefer not having this macro at all and just open-code the contents. If you use traditional struct initializers, the amount of code is almost exactly the same.
> > >> + pd = platform_device_alloc("dw_dmac", instance); > >> + if (!pd) { > >> + dev_err(&pdev->dev, "can't allocate dw_dmac platform device\n"); > >> + ret = -ENOMEM; > >> + goto err0; > >> + } > > > > Is this the correct approach? I doubt... We are creating a platform > > device from a > > pci driver... Don't know if it can lead to some issues within kernel. > > > > Lets call the specialist for his comments :) > > @Arnd: Can you please help us here? > This approach is used among different drivers in kernel. As first > example that comes to my mind you could consider chipidea USB driver > (drivers/usb/chipidea).
Yes, this is fine for a PCI device with multiple logical devices. You could also use the MFD framework if that results in smaller code. For a driver that can be either a platform device or a pci device with no other sub-devices, I would however recommend having a common initialization function for stuff that can be called from either bus_type but with no extra level of indirection.
Arnd
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