RE: [PATCH 6/6 v8] iommu/fsl: Freescale PAMU driver and IOMMU API implementation.

Sethi Varun-B16395
2013-02-27T11:56:19Z

> -----Original Message-----
> From: Stuart Yoder [mailto:b08248@gmail.com]
> Sent: Wednesday, February 27, 2013 4:03 AM
> To: Sethi Varun-B16395
> Cc: iommu@lists.linux-foundation.org; linuxppc-dev@lists.ozlabs.org;
> linux-kernel@vger.kernel.org; Wood Scott-B07421; Joerg Roedel; Yoder
> Stuart-B08248
> Subject: Re: [PATCH 6/6 v8] iommu/fsl: Freescale PAMU driver and IOMMU
> API implementation.
>
> Have not got through the entire file, but have a few comments...
>
> +/*
> + * Set the PAACE type as primary and set the coherency required domain
> + * attribute
> + */
> +static void pamu_setup_default_xfer_to_host_ppaace(struct paace
> +*ppaace) {
> + set_bf(ppaace->addr_bitfields, PAACE_AF_PT, PAACE_PT_PRIMARY);
> +
> + set_bf(ppaace->domain_attr.to_host.coherency_required,
> PAACE_DA_HOST_CR,
> + PAACE_M_COHERENCE_REQ);
> +}
> +
> +/*
> + * Set the PAACE type as secondary and set the coherency required
> +domain
> + * attribute.
> + */
> +static void pamu_setup_default_xfer_to_host_spaace(struct paace
> +*spaace) {
> + set_bf(spaace->addr_bitfields, PAACE_AF_PT, PAACE_PT_SECONDARY);
> + set_bf(spaace->domain_attr.to_host.coherency_required,
> PAACE_DA_HOST_CR,
> + PAACE_M_COHERENCE_REQ);
> +}
>
> Can we change the names of the above functions... I know there is some
> history
> with the name, but "xfer_to_host" is confusing.
>
> Maybe just call them:
>
> pamu_init_paace()
> pamu_init_spaace()
>
[Sethi Varun-B16395] ok, will change the function names.

> > +/**
> > + * pamu_config_spaace() - Sets up SPAACE entry for specified
> > +subwindow
> > + *
> > + * @liodn: Logical IO device number
> > + * @subwin_cnt: number of sub-windows associated with dma-window
> > + * @subwin_addr: starting address of subwindow
> > + * @subwin_size: size of subwindow
> > + * @omi: Operation mapping index
> > + * @rpn: real (true physical) page number
> > + * @snoopid: snoop id for hardware coherency -- if ~snoopid == 0 then
> > + * snoopid not defined
> > + * @stashid: cache stash id for associated cpu
> > + * @enable: enable/disable subwindow after reconfiguration
> > + * @prot: sub window permissions
> > + *
> > + * Returns 0 upon success else error code < 0 returned */ int
> > +pamu_config_spaace(int liodn, u32 subwin_cnt, u32 subwin_addr,
> > + phys_addr_t subwin_size, u32 omi, unsigned long
> rpn,
> > + u32 snoopid, u32 stashid, int enable, int prot)
> > +{
> > + struct paace *paace;
> > +
> > + /* setup sub-windows */
> > + if (!subwin_cnt) {
> > + pr_err("Invalid subwindow count\n");
> > + return -EINVAL;
> > + }
> > +
> > + paace = pamu_get_ppaace(liodn);
> > + if (subwin_addr > 0 && subwin_addr < subwin_cnt && paace) {
>
> Why is the comparison subwin_addr < subwin_cnt? Seems wrong...
>
[Sethi Varun-B16395] It's actually the subwindow index. I will rename the variable.

> > + paace = pamu_get_spaace(paace, subwin_addr - 1);
> > +
> > + if (paace && !(paace->addr_bitfields & PAACE_V_VALID))
> {
> > + pamu_setup_default_xfer_to_host_spaace(paace);
> > + set_bf(paace->addr_bitfields, SPAACE_AF_LIODN,
> liodn);
> > + }
> > + }
> > +
> > + if (!paace) {
> > + pr_err("Invalid liodn entry\n");
> > + return -ENOENT;
> > + }
> > +
> > + if (!enable && prot == PAACE_AP_PERMS_DENIED) {
> > + if (subwin_addr > 0)
> > + set_bf(paace->addr_bitfields, PAACE_AF_V,
> > + PAACE_V_INVALID);
> > + else
> > + set_bf(paace->addr_bitfields, PAACE_AF_AP,
> > + prot);
> > + mb();
> > + return 0;
> > + }
>
> Can you add a comment to the above if statement...when is this function
> called with PAACE_AP_PERMS_DENIED?
>
[Sethi Varun-B16395] Actually, this piece of code is redundant in case of the window based API. I will remove this. PAACE_AP_PERMS_DENIED is primarily used for disabling the primary subwindow.

-Varun