linux-kernel - Re: [PATCH 1/4] fpga mgr: Introduce FPGA capabilities

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Message-ID: <CAAtXAHeX08ZxGceXvqkdNwsVHdOpczxx5fvFapLy74n1_4R-CA@mail.gmail.com>
Date:   Mon, 14 Nov 2016 09:26:59 -0800
From:   Moritz Fischer <moritz.fischer@...us.com>
To:     atull <atull@...nsource.altera.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        moritz.fischer.private@...il.com,
        Michal Simek <michal.simek@...inx.com>,
        Sören Brinkmann <soren.brinkmann@...inx.com>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Julia Cartwright <julia@...com>
Subject: Re: [PATCH 1/4] fpga mgr: Introduce FPGA capabilities

Hi Alan,

On Mon, Nov 14, 2016 at 6:06 AM, atull <atull@...nsource.altera.com> wrote:
> On Mon, 7 Nov 2016, Moritz Fischer wrote:
>
>> Add FPGA capabilities as a way to express the capabilities
>> of a given FPGA manager.
>>
>> Removes code duplication by comparing the low-level driver's
>> capabilities at the framework level rather than having each driver
>> check for supported operations in the write_init() callback.
>>
>> This allows for extending with additional capabilities, similar
>> to the the dmaengine framework's implementation.
>>
>> Signed-off-by: Moritz Fischer <moritz.fischer@...us.com>
>> Cc: Alan Tull <atull@...nsource.altera.com>
>> Cc: Michal Simek <michal.simek@...inx.com>
>> Cc: Sören Brinkmann <soren.brinkmann@...inx.com>
>> Cc: linux-kernel@...r.kernel.org
>> Cc: linux-arm-kernel@...ts.infradead.org
>> ---
>>
>> Changes from RFC:
>> * in the RFC the caps weren't actually stored into the struct fpga_mgr
>>
>> Note:
>>
>> If people disagree on the typedef being a 'false positive' I can fix
>> that in a future rev of the patchset.
>>
>> Thanks,
>>
>>     Moritz
>>
>> ---
>>  drivers/fpga/fpga-mgr.c       | 15 ++++++++++++++
>>  drivers/fpga/socfpga.c        | 10 +++++-----
>>  drivers/fpga/zynq-fpga.c      |  7 ++++++-
>>  include/linux/fpga/fpga-mgr.h | 46 ++++++++++++++++++++++++++++++++++++++++++-
>>  4 files changed, 71 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/fpga/fpga-mgr.c b/drivers/fpga/fpga-mgr.c
>> index 953dc91..ed57c17 100644
>> --- a/drivers/fpga/fpga-mgr.c
>> +++ b/drivers/fpga/fpga-mgr.c
>> @@ -49,6 +49,18 @@ int fpga_mgr_buf_load(struct fpga_manager *mgr, u32 flags, const char *buf,
>>       struct device *dev = &mgr->dev;
>>       int ret;
>>
>> +     if (flags & FPGA_MGR_PARTIAL_RECONFIG &&
>> +         !fpga_mgr_has_cap(FPGA_MGR_CAP_PARTIAL_RECONF, mgr->caps)) {
>> +             dev_err(dev, "Partial reconfiguration not supported\n");
>> +             return -ENOTSUPP;
>> +     }
>> +
>> +     if (flags & FPGA_MGR_FULL_RECONFIG &&
>> +         !fpga_mgr_has_cap(FPGA_MGR_CAP_FULL_RECONF, mgr->caps)) {
>> +             dev_err(dev, "Full reconfiguration not supported\n");
>> +             return -ENOTSUPP;
>> +     }
>> +
>
> Could you move the checks to their own function like
> 'fpga_mgr_check_caps()' or something?  I really like it if we can keep
> the functions short, like a screen or so where it's practicle to do
> so and I could see the number of caps growing here.

Absolutely. Great suggestion.

> The only counter argument I could think of is if a cap affects the sequence
> in this function.  Hmmm...

Oh you mean the cap being there affecting the sequence in *this* function?
I'd suggest we address that when we run into a cap that requires this.

Cheers,

Moritz