Re: [PATCH v2 07/11] openrisc: mm: Convert to GENERIC_IOREMAP

Baoquan He
2022-08-29T08:18:48Z

On 08/29/22 at 06:42am, Stafford Horne wrote:
> On Mon, Aug 29, 2022 at 09:40:24AM +0800, Baoquan He wrote:
> > On 08/21/22 at 12:03am, Christoph Hellwig wrote:
> > > > + if (unlikely(!mem_init_done)) {
> > > > if ((fixmaps_used + (size >> PAGE_SHIFT)) > FIX_N_IOREMAPS)
> > > > + return IOMEM_ERR_PTR(ret);
> > > > v = fix_to_virt(FIX_IOREMAP_BEGIN + fixmaps_used);
> > > > fixmaps_used += (size >> PAGE_SHIFT);
> > > >
> > > > + if (ioremap_page_range(v, v + size, p, __pgprot(*prot_val))) {
> > > > fixmaps_used -= (size >> PAGE_SHIFT);
> > > > + return IOMEM_ERR_PTR(ret);
> > > > + }
> > > > +
> > > > + return (void __iomem *)(offset + (char *)v);
> > > > }
> > >
> > > This code needs to go away, and all very early boot uses of ioremap
> > > need to switch to use early_ioremap insted.
> >
> > Makes sense. On openrisc, the thing is I didn't find one place where
> > ioremap() is called in arch code. I can cut the early ioremap out and
> > wrap into a separate early_ioremap() function, however I don't know
> > where to put it. Not sure if I miss anything or openrisc doesn't really
> > need early ioremap.
>
> Hi,
>
> I don't know of any early_ioremap usage either in openrisc, maybe some drivers
> use it? However, we do not initialize any early_ioremap infrastructure in
> openrisc so that may cause issues if it is used.

The variable mem_init_done indicates if mem_init() is called or not.
Driver should only initialize after mem_init(). With my understanding,
the early ioremap is only needed by arch code.
>
> We can try to remove it all. I tested these below additional changes and they
> work, if you want to add them we can see if kbuild robots pick anything up.

Very helpful information. Then I will remove the !mem_init_done part
code as you listed below, let's see how test robots react. Thanks a lot.

>
> -Stafford
>
> diff --git a/arch/openrisc/mm/ioremap.c b/arch/openrisc/mm/ioremap.c
> index bc41660e1fb0..ffe6d5e2b5fe 100644
> --- a/arch/openrisc/mm/ioremap.c
> +++ b/arch/openrisc/mm/ioremap.c
> @@ -22,14 +22,10 @@
>
> extern int mem_init_done;
>
> -static unsigned int fixmaps_used __initdata;
> -
> void __iomem *
> arch_ioremap(phys_addr_t *paddr, size_t size, unsigned long *prot_val)
> {
> - phys_addr_t p;
> - unsigned long v;
> - unsigned long offset, last_addr, addr = *paddr;
> + unsigned long last_addr, addr = *paddr;
> int ret = -EINVAL;
>
> /* Don't allow wraparound or zero size */
> @@ -37,27 +33,6 @@ arch_ioremap(phys_addr_t *paddr, size_t size, unsigned long *prot_val)
> if (!size || last_addr < addr)
> return IOMEM_ERR_PTR(ret);
>
> - /*
> - * Mappings have to be page-aligned
> - */
> - offset = addr & ~PAGE_MASK;
> - p = addr & PAGE_MASK;
> - size = PAGE_ALIGN(last_addr + 1) - p;
> -
> - if (unlikely(!mem_init_done)) {
> - if ((fixmaps_used + (size >> PAGE_SHIFT)) > FIX_N_IOREMAPS)
> - return IOMEM_ERR_PTR(ret);
> - v = fix_to_virt(FIX_IOREMAP_BEGIN + fixmaps_used);
> - fixmaps_used += (size >> PAGE_SHIFT);
> -
> - if (ioremap_page_range(v, v + size, p, __pgprot(*prot_val))) {
> - fixmaps_used -= (size >> PAGE_SHIFT);
> - return IOMEM_ERR_PTR(ret);
> - }
> -
> - return (void __iomem *)(offset + (char *)v);
> - }
> -
> return NULL;
> }
>
>