RE: [PATCH v2 1/6] usb: host: xhci: add a platform-private pointer field

[Yoshihiro Shimoda]

Hi Greg,

> From: Yoshihiro Shimoda
> Sent: Monday, October 19, 2015 6:11 PM
> 
> Hi Greg,
> 
> > Sent: Saturday, October 17, 2015 3:38 PM
> >
> > On Wed, Oct 07, 2015 at 08:38:53PM +0900, Yoshihiro Shimoda wrote:
> > > This patch adds an xhci->priv field for storing the of_device_id.data
> > > pointer. This will simplify the code to match platform specific
> > > variables (e.g. platform type and firmware name).
> > >
> > > Signed-off-by: Yoshihiro Shimoda 
> > > ---
> > >  drivers/usb/host/xhci.h | 3 +++
> > >  1 file changed, 3 insertions(+)
> > >
> > > diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
> > > index 51093df..da227ba 100644
> > > --- a/drivers/usb/host/xhci.h
> > > +++ b/drivers/usb/host/xhci.h
> > > @@ -1653,6 +1653,9 @@ struct xhci_hcd {
> > >   u32 port_status_u0;
> > >  /* Compliance Mode Timer Triggered every 2 seconds */
> > >  #define COMP_MODE_RCVRY_MSECS 2000
> > > +
> > > + /* Store of_device_id.data pointer as xhci-plat private data */
> > > + const void  *priv;
> > >  };
> >
> > Why can't we do what we do with the other *_hcd structures and pad out
> > the end of the structure as needed with the following:
> > /* platform-specific data -- must come last */
> > unsigned long   priv[0] __aligned(sizeof(s64));
> >
> > and then ask for the requested amount of space depending on the platform
> > being used?
> 
> Since I found the following comment from Thomas before I submitted,
> I didn't add such the other *_hcd structures to avoid complicate.
> http://thread.gmane.org/gmane.linux.kernel/1697250/focus=73028
> (This comment was written in last year though...)
> 
> The current code has "extra_priv_size" like the following patch.
> So, can we add "priv" to xhci_hcd like the other *_hcd structures?
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=cd33a32157e42483ffea31e32b1cee4f11ff9592
> 
> Anyway, I will investigate this "extra_priv_size".

I investgated this topic.
I found that the current code can add such the other *_hcd structures using the 
"extra_priv_size".
(In other words, the comment from Thomas in last year is not fit with the 
current xhci driver code.)

However, the current implementation is strange to me:
 - The hcd_priv_size in xhci.c is sizeof(struct xhci_hcd *).
 - The extra_priv_size in xhci-plat.c and xhci-pci are sizeof(struct xhci_hcd).

In this means, actual hcd_priv_size in the xhci driver is:
 sizeof(struct xhci_hcd) + sizeof(struct xhci_hcd *)

I don't think that the "+ sizeof(struct xhci_hcd *)" is needed.
Is my understanding correct? If so, I will fix this and add such a patch into 
my v3 patch set.

Best regards,
Yoshihiro Shimoda

> Best regards,
> Yoshihiro Shimoda
> 
> > thanks,
> >
> > greg k-h
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RE: [PATCH v2 1/6] usb: host: xhci: add a platform-private pointer field

[Yoshihiro Shimoda]

Hi Greg,

> Sent: Saturday, October 17, 2015 3:38 PM
> 
> On Wed, Oct 07, 2015 at 08:38:53PM +0900, Yoshihiro Shimoda wrote:
> > This patch adds an xhci->priv field for storing the of_device_id.data
> > pointer. This will simplify the code to match platform specific
> > variables (e.g. platform type and firmware name).
> >
> > Signed-off-by: Yoshihiro Shimoda 
> > ---
> >  drivers/usb/host/xhci.h | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
> > index 51093df..da227ba 100644
> > --- a/drivers/usb/host/xhci.h
> > +++ b/drivers/usb/host/xhci.h
> > @@ -1653,6 +1653,9 @@ struct xhci_hcd {
> > u32 port_status_u0;
> >  /* Compliance Mode Timer Triggered every 2 seconds */
> >  #define COMP_MODE_RCVRY_MSECS 2000
> > +
> > +   /* Store of_device_id.data pointer as xhci-plat private data */
> > +   const void  *priv;
> >  };
> 
> Why can't we do what we do with the other *_hcd structures and pad out
> the end of the structure as needed with the following:
>   /* platform-specific data -- must come last */
>   unsigned long   priv[0] __aligned(sizeof(s64));
> 
> and then ask for the requested amount of space depending on the platform
> being used?

Since I found the following comment from Thomas before I submitted,
I didn't add such the other *_hcd structures to avoid complicate.
http://thread.gmane.org/gmane.linux.kernel/1697250/focus=73028
(This comment was written in last year though...)

The current code has "extra_priv_size" like the following patch.
So, can we add "priv" to xhci_hcd like the other *_hcd structures?
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=cd33a32157e42483ffea31e32b1cee4f11ff9592

Anyway, I will investigate this "extra_priv_size".

Best regards,
Yoshihiro Shimoda

> thanks,
> 
> greg k-h
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Re: [PATCH v2 1/6] usb: host: xhci: add a platform-private pointer field

[Greg KH]

On Wed, Oct 07, 2015 at 08:38:53PM +0900, Yoshihiro Shimoda wrote:
> This patch adds an xhci->priv field for storing the of_device_id.data
> pointer. This will simplify the code to match platform specific
> variables (e.g. platform type and firmware name).
> 
> Signed-off-by: Yoshihiro Shimoda 
> ---
>  drivers/usb/host/xhci.h | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
> index 51093df..da227ba 100644
> --- a/drivers/usb/host/xhci.h
> +++ b/drivers/usb/host/xhci.h
> @@ -1653,6 +1653,9 @@ struct xhci_hcd {
>   u32 port_status_u0;
>  /* Compliance Mode Timer Triggered every 2 seconds */
>  #define COMP_MODE_RCVRY_MSECS 2000
> +
> + /* Store of_device_id.data pointer as xhci-plat private data */
> + const void  *priv;
>  };

Why can't we do what we do with the other *_hcd structures and pad out
the end of the structure as needed with the following:
/* platform-specific data -- must come last */
unsigned long   priv[0] __aligned(sizeof(s64));

and then ask for the requested amount of space depending on the platform
being used?

thanks,

greg k-h
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