This patch set introduces a new request_atomic() interface for the
MMC host controller, which is used to submit a request to host in
the atomic context, such as in the irq hard handler, to reduce the
request latency.
Any comments are welcome. Thanks.
Note: Adrian pointed out that it is not good if moving the polling of
inhibit bits in sdhci_send_command() into the interrupt context, but
now I have not found a better way to address Adrian's concern. Moveover
this is an unusual abnormal case and the original code has the same
problem, so I plan to create another patch set to talk about and fix
this issue.
Changes from v1:
- Re-split the changes to make them more clear suggested by Ulf.
- Factor out the auto CMD23 checking into a separate function.
Baolin Wang (3):
mmc: host: Introduce the request_atomic() for the host
mmc: host: sdhci: Implement the request_atomic() API
mmc: host: sdhci-sprd: Implement the request_atomic() API
drivers/mmc/host/mmc_hsq.c | 5 ++++-
drivers/mmc/host/sdhci-sprd.c | 23 ++++++++++++++++++++---
drivers/mmc/host/sdhci.c | 27 +++++++++++++++++++--------
drivers/mmc/host/sdhci.h | 1 +
include/linux/mmc/host.h | 3 +++
5 files changed, 47 insertions(+), 12 deletions(-)
--
1.9.1
On 17/03/20 12:14 pm, Baolin Wang wrote:
> This patch set introduces a new request_atomic() interface for the
> MMC host controller, which is used to submit a request to host in
> the atomic context, such as in the irq hard handler, to reduce the
> request latency.
>
> Any comments are welcome. Thanks.
>
> Note: Adrian pointed out that it is not good if moving the polling of
> inhibit bits in sdhci_send_command() into the interrupt context, but
> now I have not found a better way to address Adrian's concern. Moveover
> this is an unusual abnormal case and the original code has the same
> problem, so I plan to create another patch set to talk about and fix
> this issue.
I tend to think the API requires the possibility for host controllers to
return "busy", so that should be sorted out first.
>
> Changes from v1:
> - Re-split the changes to make them more clear suggested by Ulf.
> - Factor out the auto CMD23 checking into a separate function.
>
> Baolin Wang (3):
> mmc: host: Introduce the request_atomic() for the host
> mmc: host: sdhci: Implement the request_atomic() API
> mmc: host: sdhci-sprd: Implement the request_atomic() API
>
> drivers/mmc/host/mmc_hsq.c | 5 ++++-
> drivers/mmc/host/sdhci-sprd.c | 23 ++++++++++++++++++++---
> drivers/mmc/host/sdhci.c | 27 +++++++++++++++++++--------
> drivers/mmc/host/sdhci.h | 1 +
> include/linux/mmc/host.h | 3 +++
> 5 files changed, 47 insertions(+), 12 deletions(-)
>
On Tue, Mar 17, 2020 at 9:25 PM Adrian Hunter <[email protected]> wrote:
>
> On 17/03/20 12:14 pm, Baolin Wang wrote:
> > This patch set introduces a new request_atomic() interface for the
> > MMC host controller, which is used to submit a request to host in
> > the atomic context, such as in the irq hard handler, to reduce the
> > request latency.
> >
> > Any comments are welcome. Thanks.
> >
> > Note: Adrian pointed out that it is not good if moving the polling of
> > inhibit bits in sdhci_send_command() into the interrupt context, but
> > now I have not found a better way to address Adrian's concern. Moveover
> > this is an unusual abnormal case and the original code has the same
> > problem, so I plan to create another patch set to talk about and fix
> > this issue.
>
> I tend to think the API requires the possibility for host controllers to
> return "busy", so that should be sorted out first.
If request_atomic() can return 'busy', the HSQ need queue a work to
dispatch this request to host again?
I am thinking if I can introduce a new flag to avoid polling the
status before sending commands, cause from the datasheet, I did not
see we should need do this if the command complete and transfer
complete interrupts are processed normally. At least on my platfrom, I
did not see the inhibit bits are set. If we meet this issue, I think
some abormal things are happened, we should give out errors. How do
you think?
> >
> > Changes from v1:
> > - Re-split the changes to make them more clear suggested by Ulf.
> > - Factor out the auto CMD23 checking into a separate function.
> >
> > Baolin Wang (3):
> > mmc: host: Introduce the request_atomic() for the host
> > mmc: host: sdhci: Implement the request_atomic() API
> > mmc: host: sdhci-sprd: Implement the request_atomic() API
> >
> > drivers/mmc/host/mmc_hsq.c | 5 ++++-
> > drivers/mmc/host/sdhci-sprd.c | 23 ++++++++++++++++++++---
> > drivers/mmc/host/sdhci.c | 27 +++++++++++++++++++--------
> > drivers/mmc/host/sdhci.h | 1 +
> > include/linux/mmc/host.h | 3 +++
> > 5 files changed, 47 insertions(+), 12 deletions(-)
> >
>
--
Baolin Wang
On 17/03/20 3:49 pm, Baolin Wang wrote:
> On Tue, Mar 17, 2020 at 9:25 PM Adrian Hunter <[email protected]> wrote:
>>
>> On 17/03/20 12:14 pm, Baolin Wang wrote:
>>> This patch set introduces a new request_atomic() interface for the
>>> MMC host controller, which is used to submit a request to host in
>>> the atomic context, such as in the irq hard handler, to reduce the
>>> request latency.
>>>
>>> Any comments are welcome. Thanks.
>>>
>>> Note: Adrian pointed out that it is not good if moving the polling of
>>> inhibit bits in sdhci_send_command() into the interrupt context, but
>>> now I have not found a better way to address Adrian's concern. Moveover
>>> this is an unusual abnormal case and the original code has the same
>>> problem, so I plan to create another patch set to talk about and fix
>>> this issue.
>>
>> I tend to think the API requires the possibility for host controllers to
>> return "busy", so that should be sorted out first.
>
> If request_atomic() can return 'busy', the HSQ need queue a work to
> dispatch this request to host again?
Sounds reasonable
>
> I am thinking if I can introduce a new flag to avoid polling the
> status before sending commands, cause from the datasheet, I did not
> see we should need do this if the command complete and transfer
> complete interrupts are processed normally. At least on my platfrom, I
> did not see the inhibit bits are set. If we meet this issue, I think
> some abormal things are happened, we should give out errors. How do
> you think?
For the atomic path, some kind of warning would be ok.
>
>>>
>>> Changes from v1:
>>> - Re-split the changes to make them more clear suggested by Ulf.
>>> - Factor out the auto CMD23 checking into a separate function.
>>>
>>> Baolin Wang (3):
>>> mmc: host: Introduce the request_atomic() for the host
>>> mmc: host: sdhci: Implement the request_atomic() API
>>> mmc: host: sdhci-sprd: Implement the request_atomic() API
>>>
>>> drivers/mmc/host/mmc_hsq.c | 5 ++++-
>>> drivers/mmc/host/sdhci-sprd.c | 23 ++++++++++++++++++++---
>>> drivers/mmc/host/sdhci.c | 27 +++++++++++++++++++--------
>>> drivers/mmc/host/sdhci.h | 1 +
>>> include/linux/mmc/host.h | 3 +++
>>> 5 files changed, 47 insertions(+), 12 deletions(-)
>>>
>>
>
>
On Tue, Mar 17, 2020 at 11:07 PM Adrian Hunter <[email protected]> wrote:
>
> On 17/03/20 3:49 pm, Baolin Wang wrote:
> > On Tue, Mar 17, 2020 at 9:25 PM Adrian Hunter <[email protected]> wrote:
> >>
> >> On 17/03/20 12:14 pm, Baolin Wang wrote:
> >>> This patch set introduces a new request_atomic() interface for the
> >>> MMC host controller, which is used to submit a request to host in
> >>> the atomic context, such as in the irq hard handler, to reduce the
> >>> request latency.
> >>>
> >>> Any comments are welcome. Thanks.
> >>>
> >>> Note: Adrian pointed out that it is not good if moving the polling of
> >>> inhibit bits in sdhci_send_command() into the interrupt context, but
> >>> now I have not found a better way to address Adrian's concern. Moveover
> >>> this is an unusual abnormal case and the original code has the same
> >>> problem, so I plan to create another patch set to talk about and fix
> >>> this issue.
> >>
> >> I tend to think the API requires the possibility for host controllers to
> >> return "busy", so that should be sorted out first.
> >
> > If request_atomic() can return 'busy', the HSQ need queue a work to
> > dispatch this request to host again?
>
> Sounds reasonable
>
> >
> > I am thinking if I can introduce a new flag to avoid polling the
> > status before sending commands, cause from the datasheet, I did not
> > see we should need do this if the command complete and transfer
> > complete interrupts are processed normally. At least on my platfrom, I
> > did not see the inhibit bits are set. If we meet this issue, I think
> > some abormal things are happened, we should give out errors. How do
> > you think?
>
> For the atomic path, some kind of warning would be ok.
OK. I will try in next version. Thanks.
> >
> >>>
> >>> Changes from v1:
> >>> - Re-split the changes to make them more clear suggested by Ulf.
> >>> - Factor out the auto CMD23 checking into a separate function.
> >>>
> >>> Baolin Wang (3):
> >>> mmc: host: Introduce the request_atomic() for the host
> >>> mmc: host: sdhci: Implement the request_atomic() API
> >>> mmc: host: sdhci-sprd: Implement the request_atomic() API
> >>>
> >>> drivers/mmc/host/mmc_hsq.c | 5 ++++-
> >>> drivers/mmc/host/sdhci-sprd.c | 23 ++++++++++++++++++++---
> >>> drivers/mmc/host/sdhci.c | 27 +++++++++++++++++++--------
> >>> drivers/mmc/host/sdhci.h | 1 +
> >>> include/linux/mmc/host.h | 3 +++
> >>> 5 files changed, 47 insertions(+), 12 deletions(-)
> >>>
> >>
> >
> >
>
--
Baolin Wang