Re: [PATCH v3 04/11] iommu/mediatek: Get regionid from larb/port id

[AngeloGioacchino Del Regno]

Il 14/02/23 10:07, AngeloGioacchino Del Regno ha scritto:
> Il 14/02/23 04:11, Yong Wu ha scritto:
> > After commit f1ad5338a4d5 ("of: Fix "dma-ranges" handling for bus
> > controllers"), the dma-ranges is not allowed for dts leaf node.
> > but we still would like to separate to different masters
> > into different iova regions.
> >
> > Thus we have to separate it by the HW larbid and portid. For example,
> > larb1/2 are in region2 and larb3 is in region3. The problem is that
> > some ports inside a larb are in region4 while some ports inside this
> > larb are in region5. Therefore I define a "iova_region_larb_msk" to help
> > record the information for each a port. Take a example for a larb:
> >   [1] = ~0: means all ports in this larb are in region1;
> >   [2] = BIT(3) | BIT(4): means port3/4 in this larb are region2;
> >   [3] = ~(BIT(3) | BIT(4)): means all the other ports except port3/4
> >                             in this larb are region3.
> >
> > This method also avoids the users forget/abuse the iova regions.
> >
> > Signed-off-by: Yong Wu <yong.wu@xxxxxxxxxxxx>
> > ---
> >   drivers/iommu/mtk_iommu.c | 47 ++++++++++++++++++++++-----------------
> >   1 file changed, 27 insertions(+), 20 deletions(-)
> >
> > diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> > index ab53edcb221f..7e2cb3b8cac8 100644
> > --- a/drivers/iommu/mtk_iommu.c
> > +++ b/drivers/iommu/mtk_iommu.c
> > @@ -8,7 +8,6 @@
> >   #include <linux/clk.h>
> >   #include <linux/component.h>
> >   #include <linux/device.h>
> > -#include <linux/dma-direct.h>
> >   #include <linux/err.h>
> >   #include <linux/interrupt.h>
> >   #include <linux/io.h>
> > @@ -212,6 +211,11 @@ struct mtk_iommu_plat_data {
> >       struct {
> >           unsigned int    iova_region_nr;
> >           const struct mtk_iommu_iova_region    *iova_region;
> > +        /*
> > +         * Indicate the correspondence between larbs/ports and regions.
> > +         * The index is same with iova_region.
>
> * The index is the same as iova_region and larb port numbers are
> * described as bit positions.
> * For example, storing BIT(0) at index 2 means "port 0 is in region 2".

Sorry, I'm reiterating because the proposed comment is wrong.

/*
 * Indicates the correspondance between larbs, ports and regions.
 *
 * The index is the same as iova_region and larb port numbers are
 * described as bit positions.
 * For example, storing BIT(0) at index 2,1 means "larb 1, port0 is in region 2".
 *              [2] = { [1] = BIT(0) }
 */


> That's most probably the best short explanation that we can give, so that nobody
> goes crazy with understanding this one.
>
> After fixing that comment, you totally deserve my
>
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
>
> Cheers!