Re: [PATCH 3/3] soc: qcom: mdt_loader: add offset to request_firmware_into_buf

[Scott Branden]

Hi Greg,

On 2019-05-23 9:56 a.m., Greg Kroah-Hartman wrote:
> On Thu, May 23, 2019 at 09:41:49AM -0700, Scott Branden wrote:
> > Hi Greg,
> >
> > On 2019-05-22 10:52 p.m., Greg Kroah-Hartman wrote:
> > > On Wed, May 22, 2019 at 07:51:13PM -0700, Scott Branden wrote:
> > > > Adjust request_firmware_into_buf API to allow for portions
> > > > of firmware file to be read into a buffer.  mdt_loader still
> > > > retricts request fo whole file read into buffer.
> > > >
> > > > Signed-off-by: Scott Branden <scott.branden@xxxxxxxxxxxx>
> > > > ---
> > > >    drivers/soc/qcom/mdt_loader.c | 7 +++++--
> > > >    1 file changed, 5 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/drivers/soc/qcom/mdt_loader.c b/drivers/soc/qcom/mdt_loader.c
> > > > index 1c488024c698..ad20d159699c 100644
> > > > --- a/drivers/soc/qcom/mdt_loader.c
> > > > +++ b/drivers/soc/qcom/mdt_loader.c
> > > > @@ -172,8 +172,11 @@ static int __qcom_mdt_load(struct device *dev, const struct firmware *fw,
> > > >    		if (phdr->p_filesz) {
> > > >    			sprintf(fw_name + fw_name_len - 3, "b%02d", i);
> > > > -			ret = request_firmware_into_buf(&seg_fw, fw_name, dev,
> > > > -							ptr, phdr->p_filesz);
> > > > +			ret = request_firmware_into_buf
> > > > +						(&seg_fw, fw_name, dev,
> > > > +						 ptr, phdr->p_filesz,
> > > > +						 0,
> > > > +						 KERNEL_PREAD_FLAG_WHOLE);
> > > So, all that work in the first 2 patches for no real change at all?  Why
> > > are these changes even needed?
> > The first two patches allow partial read of files into memory.
> >
> > Existing kernel drivers haven't need such functionality so, yes, there
> > should be no real change
> >
> > with first two patches other than adding such partial file read support.
> >
> > We have a new driver in development which needs partial read of files
> > supported in the kernel.
> As I said before, I can not take new apis without any in-kernel user.
> So let's wait for your new code that thinks it needs this, and then we
> will be glad to evaluate all of this at that point in time.

I have submitted all the necessary patches you requested here.

These include first adding tests for existing API that never had a 
kernel selftest:

https://lkml.org/lkml/2019/8/22/1367

Followed by API enhancement, tests updated, and a new driver requiring 
enhanced API:

https://lkml.org/lkml/2019/8/22/1404

> To do so otherwise is to have loads of unused "features" aquiring cruft
> in the kernel source, and you do not want that.
>
> thanks,
>
> greg k-h

Thanks,

Scott