From: Zhao Qiang <qiang.zhao@freescale.com>
To: Laura Abbott <labbott@redhat.com>, Scott Wood <scottwood@freescale.com>
CC: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
        "lauraa@codeaurora.org" <lauraa@codeaurora.org>,
        Xiaobo Xie <X.Xie@freescale.com>,
        "benh@kernel.crashing.org" <benh@kernel.crashing.org>,
        Li Leo <LeoLi@freescale.com>, "paulus@samba.org" <paulus@samba.org>
Subject: RE: [PATCH v6 3/3] qe_common: add qe_muram_ functions to manage muram
Thread-Topic: [PATCH v6 3/3] qe_common: add qe_muram_ functions to manage
 muram
Thread-Index: AQHQ3lE08qg+K0DuDEa/oy40LAO0yp4bzaWAgAA3LDA=
Date: Tue, 25 Aug 2015 03:03:09 +0000
Message-ID: <SN1PR0301MB1550C9087AFB9FEB6CD1B0899B610@SN1PR0301MB1550.namprd03.prod.outlook.com>
References: <1440408703-6113-1-git-send-email-qiang.zhao@freescale.com>
 <1440408703-6113-3-git-send-email-qiang.zhao@freescale.com>
 <55DBA98D.1070202@redhat.com>
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> -----Original Message-----
> From: Laura Abbott [mailto:labbott@redhat.com]
> Sent: Tuesday, August 25, 2015 7:32 AM
> To: Zhao Qiang-B45475; Wood Scott-B07421
> Cc: linux-kernel@vger.kernel.org; linuxppc-dev@lists.ozlabs.org;
> lauraa@codeaurora.org; Xie Xiaobo-R63061; benh@kernel.crashing.org; Li
> Yang-Leo-R58472; paulus@samba.org
> Subject: Re: [PATCH v6 3/3] qe_common: add qe_muram_ functions to manage
> muram
> 
> On 08/24/2015 02:31 AM, Zhao Qiang wrote:
> 
> 
> > +out:
> > +	of_node_put(np);
> > +	return ret;
> > +}
> > +
> > +/**
> > + * qe_muram_alloc - allocate the requested size worth of multi-user
> > +ram
> > + * @size: number of bytes to allocate
> > + * @align: requested alignment, in bytes
> > + *
> > + * This function returns an offset into the muram area.
> > + * Use qe_dpram_addr() to get the virtual address of the area.
> > + * Use qe_muram_free() to free the allocation.
> > + */
> > +unsigned long qe_muram_alloc(unsigned long size, unsigned long align)
> > +{
> > +	unsigned long start;
> > +	unsigned long flags;
> > +	struct muram_block *entry;
> > +
> > +	spin_lock_irqsave(&qe_muram_lock, flags);
> > +	muram_pool_data.align = align;
> > +	start = gen_pool_alloc(muram_pool, size);
> 
> The advantage of creating gen_pool_alloc_data was so that you could pass
> in the align automatically without having to modify the structure.
> Is there a reason you aren't using that?
> 
> > +	memset(qe_muram_addr(start), 0, size);
> 
> There doesn't seem to be a check for allocation failure from the
> gen_alloc.

gen_pool_alloc will return 0 if there is error, but if the address returned is 
just 0x0, it can't distinguish it is address or error.

> 
> > +	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
> > +	if (!entry)
> > +		goto out;
> > +	entry->start = start;
> > +	entry->size = size;
> > +	list_add(&entry->head, &muram_block_list);
> 
> What's the point of keeping the block list anyway? It's used only in this
> file and it only seems to duplicate what gen_alloc is doing internally.
> Is there some lookup functionality you still need? Could you use a
> gen_alloc API to do so?

I need to record the size when allocation, so when free the block, I can get 
The right size for the block, and pass the right size to 
gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size).

> 
> 
> Thanks,
> Laura
Thanks 
Zhao
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