Re: [PATCH] fsl-diu-fb: Update Freescale DIU driver to usepage_alloc_exact()

From: Andrew Morton
Date: Mon Jun 30 2008 - 16:25:10 EST


On Tue, 24 Jun 2008 11:44:13 -0500
Timur Tabi <timur@xxxxxxxxxxxxx> wrote:

> Update the Freescale DIU driver to use page_alloc_exact() to allocate a
> DMA buffer. This also eliminates the rheap-based memory allocator. We
> can do this now because commit 6ccf61f9 allows us to allocate 8MB physically-
> contiguous memory blocks.
>
> Signed-off-by: Timur Tabi <timur@xxxxxxxxxxxxx>
> ---
>
> My other patch, "Add alloc_pages_exact() and free_pages_exact()", must be
> applied first, otherwise drivers/video/fsl-diu-fb.c will not compile.
>
> drivers/video/fsl-diu-fb.c | 59 +++++++++++++++----------------------------
> 1 files changed, 21 insertions(+), 38 deletions(-)
>
> diff --git a/drivers/video/fsl-diu-fb.c b/drivers/video/fsl-diu-fb.c
> index 0a27853..d15d265 100644
> --- a/drivers/video/fsl-diu-fb.c
> +++ b/drivers/video/fsl-diu-fb.c
> @@ -279,58 +279,41 @@ static struct diu_hw dr = {
>
> static struct diu_pool pool;
>
> -/* To allocate memory for framebuffer. First try __get_free_pages(). If it
> - * fails, try rh_alloc. The reason is __get_free_pages() cannot allocate
> - * very large memory (more than 4MB). We don't want to allocate all memory
> - * in rheap since small memory allocation/deallocation will fragment the
> - * rheap and make the furture large allocation fail.
> +/**
> + * fsl_diu_alloc - allocate memory for the DIU
> + * @size: number of bytes to allocate
> + * @param: returned physical address of memory
> + *
> + * This function allocates a physically-contiguous block of memory.
> */
> -
> -void *fsl_diu_alloc(unsigned long size, phys_addr_t *phys)
> +static void *fsl_diu_alloc(size_t size, phys_addr_t *phys)
> {
> void *virt;
>
> - pr_debug("size=%lu\n", size);
> + pr_debug("size=%u\n", size);

Nope, this will generate warnings on some architectures.

The way to print a size_t is with %zu or %zd. I guess the latter is for
ssize_t.


> - virt = (void *)__get_free_pages(GFP_DMA | __GFP_ZERO, get_order(size));
> + virt = alloc_pages_exact(size, GFP_DMA | __GFP_ZERO);
> if (virt) {
> *phys = virt_to_phys(virt);
> - pr_debug("virt %p, phys=%llx\n", virt, (uint64_t) *phys);
> - return virt;
> - }
> - if (!diu_ops.diu_mem) {
> - printk(KERN_INFO "%s: no diu_mem."
> - " To reserve more memory, put 'diufb=15M' "
> - "in the command line\n", __func__);
> - return NULL;
> - }
> -
> - virt = (void *)rh_alloc(&diu_ops.diu_rh_info, size, "DIU");
> - if (virt) {
> - *phys = virt_to_bus(virt);
> - memset(virt, 0, size);
> + pr_debug("virt=%p, phys=%llx\n", virt, (uint64_t) *phys);

This is also incorrect. We cannot pass u64 or uint64_t into printk at
all. We do not know what type the architectures uses to implement
them. It should be cast to a known type. In this case `unsigned long
long'.


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