Re: [PATCH v4 18/20] crypto: qce: Defer probing if BAM dma channel is not yet initialized

[Vladimir Zapolskiy]

Hi Bhupesh,

On 10/14/21 10:40 AM, Bhupesh Sharma wrote:
> Hi Vladimir,
>
> On Thu, 14 Oct 2021 at 02:19, Vladimir Zapolskiy
> <vladimir.zapolskiy@xxxxxxxxxx> wrote:
> > Hi Bhupesh,
> >
> > On 10/13/21 1:55 PM, Bhupesh Sharma wrote:
> > > Since the Qualcomm qce crypto driver needs the BAM dma driver to be
> > > setup first (to allow crypto operations), it makes sense to defer
> > > the qce crypto driver probing in case the BAM dma driver is not yet
> > > probed.
> > >
> > > Move the code leg requesting dma channels earlier in the
> > > probe() flow. This fixes the qce probe failure issues when both qce
> > > and BMA dma are compiled as static part of the kernel.
> > >
> > > Cc: Thara Gopinath <thara.gopinath@xxxxxxxxxx>
> > > Cc: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
> > > Signed-off-by: Bhupesh Sharma <bhupesh.sharma@xxxxxxxxxx>
> > > ---
> > >    drivers/crypto/qce/core.c | 20 ++++++++++++--------
> > >    1 file changed, 12 insertions(+), 8 deletions(-)
> > >
> > > diff --git a/drivers/crypto/qce/core.c b/drivers/crypto/qce/core.c
> > > index cb8c77709e1e..c6f686126fc9 100644
> > > --- a/drivers/crypto/qce/core.c
> > > +++ b/drivers/crypto/qce/core.c
> > > @@ -209,9 +209,19 @@ static int qce_crypto_probe(struct platform_device *pdev)
> > >        if (ret < 0)
> > >                return ret;
> > >
> > > +     /* qce driver requires BAM dma driver to be setup first.
> >
> > I believe a multi-line block of comments should be started with '/*' line,
> > for reference please take a look at Documentation/process/coding-style.rst
>
> There are exceptions to this rule as well. For e.g. see most of the
> networking drivers and the multi-line comment styles there :) .
>
> There is a very interesting LWN article on the same :
> https://lwn.net/Articles/694755/
> Note that 'crypto/' and 'drivers/crypto' use these non-standard
> multi-line comments quite often as well.

Ah, yes, I agree here, thank you for the reminder! IIRC crypto drivers
kind of belong to netdev domain, at least in relation to the accepted
coding style.

> That said, I have no strong opinion on using either style. Although, I
> found one of the points raised by the networking maintainer during one
> of my patch reviews earlier quite useful - 'keeping the top line in a
> multi-line comment blank, wastes precious screen space while reading
> and reviewing the patch'.

--
Best wishes,
Vladimir