lkml.org 
[lkml]   [2009]   [Jan]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/6] omap iommu: tlb and pagetable primitives
A few more simple comments...

On Fri, Jan 16, 2009 at 10:37:09AM +0200, Hiroshi DOYU wrote:
> +struct iommu_platform_data {
> + char *name;

const?

> + char *clk_name;

const?

> + int nr_tlb_entries;
> +};

...

> +int install_iommu_arch(const struct iommu_functions *ops)
> +{
> + if (arch_iommu)
> + return -EBUSY;
> +
> + arch_iommu = ops;
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(install_iommu_arch);

Exported functions should have some documentation in the standard kernel
documentation format. See Documentation/kernel-doc-nano-HOWTO.txt

> +static int iommu_enable(struct iommu *obj)
> +{
> + int err;
> +
> + BUG_ON(!arch_iommu || !arch_iommu->enable);

Are these run-time BUG_ON checks really worth it? BUG_ON is effectively:

if (condition_is_true)
cause_a_null_pointer_dereference;
So, if you're checking for pointers you're about dereference being NULL,
there's little point - dereferencing the when they're NULL will cause an
oops, and you won't have the overhead of the runtime tests checking them
for NULL. Ditto elsewhere in this file.

> +static u32 *iopte_alloc(struct iommu *obj, u32 *iopgd, u32 da)
> +{
> + u32 *iopte;
> +
> + /* a table has already existed */
> + if (*iopgd)
> + goto pte_ready;
> +
> + /*
> + * do the allocation outside the page table lock
> + */
> + spin_unlock(&obj->page_table_lock);
> + iopte = kmem_cache_zalloc(iopte_cachep, GFP_KERNEL);
> + spin_lock(&obj->page_table_lock);
> +
> + if (!*iopgd) {
> + if (!iopte)
> + return ERR_PTR(-ENOMEM);
> +
> + *iopgd = virt_to_phys(iopte) | IOPGD_TABLE;
> + flush_iopgd_range(iopgd, iopgd);
> +
> +#ifdef DEBUG_VERBOSE
> + dev_dbg(obj->dev, "%s:\ta new pte:%p\n", __func__, iopte);
> +#endif

Not sure wrapping these in DEBUG_VERBOSE is necessary. dev_dbg() is a
no-op unless DEBUG is defined.

> +#ifdef DEBUG
> +static void dump_tlb_entries(struct iommu *obj)
> +{
> + int i;
> + struct iotlb_lock l;
> +
> + clk_enable(obj->clk);
> +
> + pr_info("%8s %8s\n", "cam:", "ram:");
> + pr_info("-----------------------------------------\n");
> +
> + for (i = 0; i < obj->nr_tlb_entries; i++) {
> + struct cr_regs cr;
> + static char buf[4096];
> +
> + iotlb_lock_get(obj, &l);
> + l.vict = i;
> + iotlb_lock_set(obj, &l);
> + iotlb_read_cr(obj, &cr);
> + if (!iotlb_cr_valid(&cr))
> + continue;
> +
> + memset(buf, 0, 4096);
> + iotlb_dump_cr(obj, &cr, buf);
> + pr_info("%s", buf);

Hmm. You call this in relation to an error, but you print everything at
'info' level. Are you sure that's correct?

> +/*
> + * OMAP Device MMU(IOMMU) detection
> + */
> +static int __devinit omap_iommu_probe(struct platform_device *pdev)
> +{
> + int err = -ENODEV;
> + void *p;
> + int irq;
> + struct iommu *obj;
> + struct resource *res;
> + struct iommu_platform_data *pdata = pdev->dev.platform_data;
> +
> + if (pdev->num_resources != 2)
> + return -EINVAL;
> +
> + obj = kzalloc(sizeof(*obj) + MMU_REG_SIZE, GFP_KERNEL);
> + if (!obj)
> + return -ENOMEM;
> +
> + obj->clk = clk_get(NULL, pdata->clk_name);

Avoid passing a NULL struct device except when you have absolutely no other
choice. &pdev->dev looks sensible. By doing this, it also provides us with
a path to fixing the OMAP clk API implementation without having to fix lots
of drivers.


\
 
 \ /
  Last update: 2009-01-17 17:09    [from the cache]
©2003-2011 Jasper Spaans