Re: [PATCH v2 1/8] mmc: sdhci: Get rid of finish_tasklet

Adrian Hunter
2019-04-02T13:12:29Z

On 2/04/19 10:59 AM, Faiz Abbas wrote:
> Hi Adrian,
>
> On 26/03/19 1:03 PM, Adrian Hunter wrote:
>> On 18/03/19 11:33 AM, Ulf Hansson wrote:
>>> + Arnd, Grygorii
>>>
>>> On Fri, 15 Feb 2019 at 20:17, Faiz Abbas <faiz_abbas@ti.com> wrote:
>>>>
>>>> sdhci.c has two bottom halves implemented. A threaded_irq for handling
>>>> card insert/remove operations and a tasklet for finishing mmc requests.
>>>> With the addition of external dma support, dmaengine APIs need to
>>>> terminate in non-atomic context before unmapping the dma buffers.
>>>>
>>>> To facilitate this, remove the finish_tasklet and move the call of
>>>> sdhci_request_done() to the threaded_irq() callback. Also move the
>>>> interrupt result variable to sdhci_host so it can be populated from
>>>> anywhere inside the sdhci_irq handler.
>>>>
>>>> Signed-off-by: Faiz Abbas <faiz_abbas@ti.com>
>>>
>>> Adrian, I think it makes sense to apply this patch, even if there is
>>> very minor negative impact throughput wise.
>>>
>>> To me, it doesn't seems like MMC/SD/SDIO has good justification for
>>> using tasklets, besides from the legacy point of view, of course.
>>> Instead, I think we should try to move all mmc hosts into using
>>> threaded IRQs.
>>>
>>> So, what do you think? Can you overlook the throughput drop and
>>> instead we can try to recover this on top with other optimizations?
>>
>> I tend to favour good results as expressed here:
>>
>> https://lkml.org/lkml/2007/6/22/360
>>
>> So I want to do optimization first.
>>
>> But performance is not the only problem with the patch. Give me a few
>> days and I will see what I can come up with.
>>
>
> Gentle ping on this.

Working on it :-)