Re: [PATCH v5 14/20] iommu/mediatek: Add mmu1 support

Yong Wu
2019-01-31T03:22:31Z

On Wed, 2019-01-30 at 10:55 -0800, Evan Green wrote:
> On Mon, Dec 31, 2018 at 7:59 PM Yong Wu <yong.wu@mediatek.com> wrote:
> >
> > Normally the M4U HW connect EMI with smi. the diagram is like below:
> > EMI
> > |
> > M4U
> > |
> > smi-common
> > |
> > -----------------
> > | | | | ...
> > larb0 larb1 larb2 larb3
> >
> > Actually there are 2 mmu cells in the M4U HW, like this diagram:
> >
> > EMI
> > ---------
> > | |
> > mmu0 mmu1 <- M4U
> > | |
> > ---------
> > |
> > smi-common
> > |
> > -----------------
> > | | | | ...
> > larb0 larb1 larb2 larb3
> >
> > This patch add support for mmu1. In order to get better performance,
> > we could adjust some larbs go to mmu1 while the others still go to
> > mmu0. This is controlled by a SMI COMMON register SMI_BUS_SEL(0x220).
> >
> > mt2712, mt8173 and mt8183 M4U HW all have 2 mmu cells. the default
> > value of that register is 0 which means all the larbs go to mmu0
> > defaultly.
> >
> > This is a preparing patch for adjusting SMI_BUS_SEL for mt8183.
> >
> > Signed-off-by: Yong Wu <yong.wu@mediatek.com>
> > ---
> > drivers/iommu/mtk_iommu.c | 47 +++++++++++++++++++++++++++++------------------
> > 1 file changed, 29 insertions(+), 18 deletions(-)
> >
> > diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> > index 66e3615..7fcef19 100644
> > --- a/drivers/iommu/mtk_iommu.c
> > +++ b/drivers/iommu/mtk_iommu.c
> > @@ -70,27 +70,32 @@
> > #define F_MISS_FIFO_ERR_INT_EN BIT(6)
> > #define F_INT_CLR_BIT BIT(12)
> >
> > -#define REG_MMU_INT_MAIN_CONTROL 0x124
> > -#define F_INT_TRANSLATION_FAULT BIT(0)
> > -#define F_INT_MAIN_MULTI_HIT_FAULT BIT(1)
> > -#define F_INT_INVALID_PA_FAULT BIT(2)
> > -#define F_INT_ENTRY_REPLACEMENT_FAULT BIT(3)
> > -#define F_INT_TLB_MISS_FAULT BIT(4)
> > -#define F_INT_MISS_TRANSACTION_FIFO_FAULT BIT(5)
> > -#define F_INT_PRETETCH_TRANSATION_FIFO_FAULT BIT(6)
> > +#define REG_MMU_INT_MAIN_CONTROL 0x124 /* mmu0 | mmu1 */
>
> The comment being on that line is kind of weird, since the comment
> really applies to the lines below it. Maybe the comment should be on
> its own line, or on the TRANSLATION_FAULT line.

Sharp eye. You are right, this comment applies the lines below.
But If I move it below, then the next line will be over 80 chars.

How about I add a "below:" like this:
> +#define REG_MMU_INT_MAIN_CONTROL 0x124 /* below: mmu0 |
mmu1 */

>
> Other than that,
> Reviewed-by: Evan Green <evgreen@chromium.org>