linux-kernel - Re: [PATCH] drm/panfrost: Use upper/lower_32

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Message-ID: <38b0aa7e-6657-2ca3-ccc9-3bfa9ae8fab8@arm.com>
Date:   Wed, 25 Aug 2021 10:06:02 +0100
From:   Steven Price <steven.price@....com>
To:     Alyssa Rosenzweig <alyssa.rosenzweig@...labora.com>,
        dri-devel@...ts.freedesktop.org
Cc:     Rob Herring <robh@...nel.org>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/panfrost: Use upper/lower_32_bits helpers

On 24/08/2021 18:26, Alyssa Rosenzweig wrote:
> Use upper_32_bits/lower_32_bits helpers instead of open-coding them.
> This is easier to scan quickly compared to bitwise manipulation, and it
> is pleasingly symmetric. I noticed this when debugging lock_region,
> which had a particularly "creative" way of writing upper_32_bits.
> 
> Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@...labora.com>

It looks like there's another case (slightly different format) in
perfcnt:

---8<---
diff --git a/drivers/gpu/drm/panfrost/panfrost_perfcnt.c b/drivers/gpu/drm/panfrost/panfrost_perfcnt.c
index 5ab03d605f57..e116a4d9b8e5 100644
--- a/drivers/gpu/drm/panfrost/panfrost_perfcnt.c
+++ b/drivers/gpu/drm/panfrost/panfrost_perfcnt.c
@@ -51,8 +51,8 @@ static int panfrost_perfcnt_dump_locked(struct panfrost_device *pfdev)
 
        reinit_completion(&pfdev->perfcnt->dump_comp);
        gpuva = pfdev->perfcnt->mapping->mmnode.start << PAGE_SHIFT;
-       gpu_write(pfdev, GPU_PERFCNT_BASE_LO, gpuva);
-       gpu_write(pfdev, GPU_PERFCNT_BASE_HI, gpuva >> 32);
+       gpu_write(pfdev, GPU_PERFCNT_BASE_LO, lower_32_bits(gpuva));
+       gpu_write(pfdev, GPU_PERFCNT_BASE_HI, upper_32_bits(gpuva));
        gpu_write(pfdev, GPU_INT_CLEAR,
                  GPU_IRQ_CLEAN_CACHES_COMPLETED |
                  GPU_IRQ_PERFCNT_SAMPLE_COMPLETED);
---8<--


With that squashed in:

Reviewed-by: Steven Price <steven.price@....com>

Thanks,

Steve

> ---
>  drivers/gpu/drm/panfrost/panfrost_job.c |  8 ++++----
>  drivers/gpu/drm/panfrost/panfrost_mmu.c | 12 ++++++------
>  2 files changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c
> index 71a72fb50e6b..763b7abfc88e 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_job.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_job.c
> @@ -137,8 +137,8 @@ static void panfrost_job_write_affinity(struct panfrost_device *pfdev,
>  	 */
>  	affinity = pfdev->features.shader_present;
>  
> -	job_write(pfdev, JS_AFFINITY_NEXT_LO(js), affinity & 0xFFFFFFFF);
> -	job_write(pfdev, JS_AFFINITY_NEXT_HI(js), affinity >> 32);
> +	job_write(pfdev, JS_AFFINITY_NEXT_LO(js), lower_32_bits(affinity));
> +	job_write(pfdev, JS_AFFINITY_NEXT_HI(js), upper_32_bits(affinity));
>  }
>  
>  static u32
> @@ -203,8 +203,8 @@ static void panfrost_job_hw_submit(struct panfrost_job *job, int js)
>  
>  	cfg = panfrost_mmu_as_get(pfdev, job->file_priv->mmu);
>  
> -	job_write(pfdev, JS_HEAD_NEXT_LO(js), jc_head & 0xFFFFFFFF);
> -	job_write(pfdev, JS_HEAD_NEXT_HI(js), jc_head >> 32);
> +	job_write(pfdev, JS_HEAD_NEXT_LO(js), lower_32_bits(jc_head));
> +	job_write(pfdev, JS_HEAD_NEXT_HI(js), upper_32_bits(jc_head));
>  
>  	panfrost_job_write_affinity(pfdev, job->requirements, js);
>  
> diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c
> index 0da5b3100ab1..c3fbe0ad9090 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
> @@ -80,8 +80,8 @@ static void lock_region(struct panfrost_device *pfdev, u32 as_nr,
>  	region |= region_width;
>  
>  	/* Lock the region that needs to be updated */
> -	mmu_write(pfdev, AS_LOCKADDR_LO(as_nr), region & 0xFFFFFFFFUL);
> -	mmu_write(pfdev, AS_LOCKADDR_HI(as_nr), (region >> 32) & 0xFFFFFFFFUL);
> +	mmu_write(pfdev, AS_LOCKADDR_LO(as_nr), lower_32_bits(region));
> +	mmu_write(pfdev, AS_LOCKADDR_HI(as_nr), upper_32_bits(region));
>  	write_cmd(pfdev, as_nr, AS_COMMAND_LOCK);
>  }
>  
> @@ -123,14 +123,14 @@ static void panfrost_mmu_enable(struct panfrost_device *pfdev, struct panfrost_m
>  
>  	mmu_hw_do_operation_locked(pfdev, as_nr, 0, ~0UL, AS_COMMAND_FLUSH_MEM);
>  
> -	mmu_write(pfdev, AS_TRANSTAB_LO(as_nr), transtab & 0xffffffffUL);
> -	mmu_write(pfdev, AS_TRANSTAB_HI(as_nr), transtab >> 32);
> +	mmu_write(pfdev, AS_TRANSTAB_LO(as_nr), lower_32_bits(transtab));
> +	mmu_write(pfdev, AS_TRANSTAB_HI(as_nr), upper_32_bits(transtab));
>  
>  	/* Need to revisit mem attrs.
>  	 * NC is the default, Mali driver is inner WT.
>  	 */
> -	mmu_write(pfdev, AS_MEMATTR_LO(as_nr), memattr & 0xffffffffUL);
> -	mmu_write(pfdev, AS_MEMATTR_HI(as_nr), memattr >> 32);
> +	mmu_write(pfdev, AS_MEMATTR_LO(as_nr), lower_32_bits(memattr));
> +	mmu_write(pfdev, AS_MEMATTR_HI(as_nr), upper_32_bits(memattr));
>  
>  	write_cmd(pfdev, as_nr, AS_COMMAND_UPDATE);
>  }
>