Query regarding ADMA descriptor allocation

Query regarding ADMA descriptor allocation

[Asutosh Das]

Hi
In sdhci_add_host function, the number of adma descriptors allocated are 
128 and each descriptor consumes 8 bytes and 1 4byte is added in the end 
like,
kmalloc((128 * 2 + 1) * 4, GFP_KERNEL);

In sdhci_adma_table_pre function, each node in sg-list is iterated and 
in case of a misaligned node, a descriptor is consumed, which means for 
a single sg-node 2 descriptors were consumed. Let's say in a situation, 
where there are multiple unaligned addresses in multiple sg nodes and 
the sg-list length is 128, wouldn't this use up all the 128 descriptors 
long before the entire sg-list is traversed ?




-- 
Sent by a consultant of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.

Re: Query regarding ADMA descriptor allocation

[Asutosh Das]

Hi
Can you please let me know if my understanding in the below question is 
correct ?

Thanks
Asutosh

On 1/11/2013 6:01 PM, Asutosh Das wrote:
> Hi
> In sdhci_add_host function, the number of adma descriptors allocated 
> are 128 and each descriptor consumes 8 bytes and 1 4byte is added in 
> the end like,
> kmalloc((128 * 2 + 1) * 4, GFP_KERNEL);
>
> In sdhci_adma_table_pre function, each node in sg-list is iterated and 
> in case of a misaligned node, a descriptor is consumed, which means 
> for a single sg-node 2 descriptors were consumed. Let's say in a 
> situation, where there are multiple unaligned addresses in multiple sg 
> nodes and the sg-list length is 128, wouldn't this use up all the 128 
> descriptors long before the entire sg-list is traversed ?
>
>
>
>


-- 
Sent by a consultant of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.

Re: Query regarding ADMA descriptor allocation

[Subhash Jadavani]

Hi Chris,

Can anyone from SDHCi confirm if the understanding below is correct or 
not? If it is than we can post a patch to fix it.

Regards,
Subhash

On 1/13/2013 5:50 PM, Asutosh Das wrote:
> Hi
> Can you please let me know if my understanding in the below question 
> is correct ?
>
> Thanks
> Asutosh
>
> On 1/11/2013 6:01 PM, Asutosh Das wrote:
>> Hi
>> In sdhci_add_host function, the number of adma descriptors allocated 
>> are 128 and each descriptor consumes 8 bytes and 1 4byte is added in 
>> the end like,
>> kmalloc((128 * 2 + 1) * 4, GFP_KERNEL);
>>
>> In sdhci_adma_table_pre function, each node in sg-list is iterated 
>> and in case of a misaligned node, a descriptor is consumed, which 
>> means for a single sg-node 2 descriptors were consumed. Let's say in 
>> a situation, where there are multiple unaligned addresses in multiple 
>> sg nodes and the sg-list length is 128, wouldn't this use up all the 
>> 128 descriptors long before the entire sg-list is traversed ?
>>
>>
>>
>>
>
>