From: Tomasz Figa <tfiga@google.com>
To: Shunqian Zheng <zhengsq@rock-chips.com>
Cc: "Joerg Roedel" <joro@8bytes.org>,
"Heiko Stübner" <heiko@sntech.de>,
"Rob Herring" <robh+dt@kernel.org>,
"Mark Rutland" <mark.rutland@arm.com>,
linux@armlinux.org.uk, 姚智情 <mark.yao@rock-chips.com>,
"David Airlie" <airlied@linux.ie>,
"simon xue" <xxm@rock-chips.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"open list:IOMMU DRIVERS" <iommu@lists.linux-foundation.org>,
devicetree@vger.kernel.org,
dri-devel <dri-devel@lists.freedesktop.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"open list:ARM/Rockchip SoC..."
<linux-rockchip@lists.infradead.org>
Subject: Re: [PATCH v2 6/7] iommu/rockchip: use DMA API to map, to flush cache
Date: Fri, 10 Jun 2016 18:10:29 +0900 [thread overview]
Message-ID: <CAAFQd5Da+Eg=eiRUgLSS_qPjGbG474KYWDC=GaAMS8A_CuQ3Mg@mail.gmail.com> (raw)
In-Reply-To: <1465392392-2003-7-git-send-email-zhengsq@rock-chips.com>
Hi,
On Wed, Jun 8, 2016 at 10:26 PM, Shunqian Zheng <zhengsq@rock-chips.com> wrote:
> Use DMA API instead of architecture internal functions like
> __cpuc_flush_dcache_area() etc.
>
> To support the virtual device like DRM the virtual slave iommu
> added in the previous patch, attaching to which the DRM can use
> it own domain->dev for dma_map_*(), dma_sync_*() even VOP is disabled.
>
> With this patch, this driver is available for ARM64 like RK3399.
>
Could we instead simply allocate coherent memory for page tables using
dma_alloc_coherent() and skip any flushing on CPU side completely? If
I'm looking correctly, the driver only reads back the page directory
when checking if there is a need to allocate new page table, so there
shouldn't be any significant penalty for disabling the cache.
Other than that, please see some comments inline.
> Signed-off-by: Shunqian Zheng <zhengsq@rock-chips.com>
> ---
> drivers/iommu/rockchip-iommu.c | 113 ++++++++++++++++++++++++++---------------
> 1 file changed, 71 insertions(+), 42 deletions(-)
>
> diff --git a/drivers/iommu/rockchip-iommu.c b/drivers/iommu/rockchip-iommu.c
> index d6c3051..aafea6e 100644
> --- a/drivers/iommu/rockchip-iommu.c
> +++ b/drivers/iommu/rockchip-iommu.c
> @@ -4,8 +4,6 @@
> * published by the Free Software Foundation.
> */
>
> -#include <asm/cacheflush.h>
> -#include <asm/pgtable.h>
> #include <linux/compiler.h>
> #include <linux/delay.h>
> #include <linux/device.h>
> @@ -61,8 +59,7 @@
> #define RK_MMU_IRQ_BUS_ERROR 0x02 /* bus read error */
> #define RK_MMU_IRQ_MASK (RK_MMU_IRQ_PAGE_FAULT | RK_MMU_IRQ_BUS_ERROR)
>
> -#define NUM_DT_ENTRIES 1024
> -#define NUM_PT_ENTRIES 1024
> +#define NUM_TLB_ENTRIES 1024 /* for both DT and PT */
Is it necessary to change this in this patch? In general, it's not a
good idea to mix multiple logical changes together.
>
> #define SPAGE_ORDER 12
> #define SPAGE_SIZE (1 << SPAGE_ORDER)
> @@ -82,7 +79,9 @@
>
> struct rk_iommu_domain {
> struct list_head iommus;
> + struct device *dev;
> u32 *dt; /* page directory table */
> + dma_addr_t dt_dma;
> spinlock_t iommus_lock; /* lock for iommus list */
> spinlock_t dt_lock; /* lock for modifying page directory table */
>
> @@ -98,14 +97,12 @@ struct rk_iommu {
> struct iommu_domain *domain; /* domain to which iommu is attached */
> };
>
> -static inline void rk_table_flush(u32 *va, unsigned int count)
> +static inline void rk_table_flush(struct device *dev, dma_addr_t dma,
> + unsigned int count)
> {
> - phys_addr_t pa_start = virt_to_phys(va);
> - phys_addr_t pa_end = virt_to_phys(va + count);
> - size_t size = pa_end - pa_start;
> + size_t size = count * 4;
It would be a good idea to specify what "count" is. I'm a bit confused
that before it meant bytes and now some multiple of 4?
Best regards,
Tomasz
next prev parent reply other threads:[~2016-06-10 9:10 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-08 13:26 [PATCH v2 0/7] fix bugs; enable iommu for ARM64 Shunqian Zheng
2016-06-08 13:26 ` [PATCH v2 1/7] iommu/rockchip: fix devm_{request,free}_irq parameter Shunqian Zheng
2016-06-10 5:30 ` Tomasz Figa
2016-06-08 13:26 ` [PATCH v2 2/7] iommu/rockchip: add map_sg callback for rk_iommu_ops Shunqian Zheng
2016-06-10 5:31 ` Tomasz Figa
2016-06-08 13:26 ` [PATCH v2 3/7] iommu/rockchip: support virtual iommu slave device Shunqian Zheng
2016-06-10 6:22 ` Tomasz Figa
2016-06-08 13:26 ` [PATCH v2 4/7] ARM: dts: rockchip: add virtual iommu for display Shunqian Zheng
2016-06-10 6:22 ` Tomasz Figa
2016-06-08 13:26 ` [PATCH v2 5/7] drm: rockchip: use common iommu api to attach iommu Shunqian Zheng
2016-06-10 8:03 ` Tomasz Figa
2016-06-08 13:26 ` [PATCH v2 6/7] iommu/rockchip: use DMA API to map, to flush cache Shunqian Zheng
2016-06-10 9:10 ` Tomasz Figa [this message]
[not found] ` <575E834C.30305@gmail.com>
2016-06-13 10:21 ` Tomasz Figa
[not found] ` <575E8B6F.1040103@gmail.com>
2016-06-13 10:41 ` Tomasz Figa
2016-06-13 10:39 ` Robin Murphy
2016-06-08 13:26 ` [PATCH v2 7/7] iommu/rockchip: enable rockchip iommu on ARM64 platform Shunqian Zheng
2016-06-10 9:12 ` Tomasz Figa
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