Hello,
On 2/17/2011 8:40 PM, Pedanekar, Hemant wrote:
> Correction: outbound --> remote
>
> linux-pci-owner@xxxxxxxxxxxxxxx wrote on :
>
>> Hello,
>>
>> linux-pci-owner@xxxxxxxxxxxxxxx wrote on Thursday, February 17, 2011 3:44
>> PM:
>>
>>> pcie_set_readrq modifies read request size in EP's capability register.
>>> Now considering a situation where this EP is to be connected to an RC
>>> whose implemented read buffer size is less than what this function
>>> programs. [As per pcie specification this buffer size can be 128-4096
>>> bytes. So an RC can have lesser buffer size]
>>> In this scenario there is no way that RC can revert this as
>>> per its capability.
>>> So , read capability should always be either programmed by enumeration
>>> during bootloader or by using postinit hook of base driver. I mean, it
>>> should be programmed by RC's driver not by EP's driver.
>>
>> I am also working on a RC device which supports max outbound
>> read request of
>> 256 bytes and have to modify this (sil) driver to set read
>> request size to
>> 256 bytes. This patch would probably help me.
>>
>> But I have one question: aren't the completors supposed to
>> respond with
>> multiple completions if the read request exceeds their buffer limit?
>>
I am also agreeing with this statement. But, I really do not know why
does a read request fails , rather to be replied by multiple packets.
What happens in your case? Does it not work, if you do not modify sil driver?
Regards
Pratyush
>> Thanks.
>> Hemant
>>
>>> Signed-off-by: Pratyush Anand <pratyush.anand@xxxxxx> ---
>>> drivers/ata/sata_sil24.c | 5 -----
>>> 1 files changed, 0 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/ata/sata_sil24.c
>> b/drivers/ata/sata_sil24.c index
>>> af41c6f..bc45e01 100644 --- a/drivers/ata/sata_sil24.c
>>> +++ b/drivers/ata/sata_sil24.c
>>> @@ -1343,11 +1343,6 @@ static int sil24_init_one(struct
>>> pci_dev *pdev, const struct pci_device_id *ent)
>>> }
>>> }
>>>
>>> - /* Set max read request size to 4096. This slightly increases
>>> - * write throughput for pci-e variants.
>>> - */
>>> - pcie_set_readrq(pdev, 4096);
>>> -
>>> sil24_init_controller(host);
>>>
>>> if (sata_sil24_msi && !pci_enable_msi(pdev)) {
>>> --
>>> 1.6.0.2--
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>
>
>
> Hemant.
>
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