Re: [PATCH v2] bus: mhi: host: don't free bhie tables during suspend/hibernation

[Jeff Hugo]

On 4/14/2025 1:32 AM, Muhammad Usama Anjum wrote:
> On 4/12/25 6:22 AM, Krishna Chaitanya Chundru wrote:
> > On 4/12/2025 12:02 AM, Muhammad Usama Anjum wrote:
> > > On 4/11/25 1:39 PM, Krishna Chaitanya Chundru wrote:
> > > > On 4/11/2025 12:32 PM, Muhammad Usama Anjum wrote:
> > > > > On 4/11/25 8:37 AM, Krishna Chaitanya Chundru wrote:
> > > > > > On 4/10/2025 8:26 PM, Muhammad Usama Anjum wrote:
> > > > > > > Fix dma_direct_alloc() failure at resume time during bhie_table
> > > > > > > allocation. There is a crash report where at resume time, the memory
> > > > > > > from the dma doesn't get allocated and MHI fails to re-initialize.
> > > > > > > There may be fragmentation of some kind which fails the allocation
> > > > > > > call.
> > > > > > >
> > > > > > > To fix it, don't free the memory at power down during suspend /
> > > > > > > hibernation. Instead, use the same allocated memory again after every
> > > > > > > resume / hibernation. This patch has been tested with resume and
> > > > > > > hibernation both.
> > > > > > >
> > > > > > > The rddm is of constant size for a given hardware. While the
> > > > > > > fbc_image
> > > > > > > size depends on the firmware. If the firmware changes, we'll free and
> > > > > > If firmware image will change between suspend and resume ?
> > > > > Yes, correct.
> > > > why the firmware image size will change between suspend & resume?
> > > > who will update the firmware image after bootup?
> > > > It is not expected behaviour.
> > > I was trying to research if the firmware can change or not. I've not
> > > found any documentation on it.
> > >
> > > If the firmare is updated in filesystem before suspend/hibernate, would
> > > the new firwmare be loaded the next time kernel resumes as the older
> > > firmware is no where to be found?
> > >
> > > What do you think about this?
> > I don't think firmware can be updated before suspend/hibernate. I don't
> > see any reason why it can be updated. If you think it can be updated
> > please quote relevant doc.
> I've not found any documentation on it. Let's wait for others to review
> and it it cannot be updated, I'll remove this part.

Wouldn't this be trivial to test?  Boot the device, go modify the 
firmware on the filesystem, then go through a suspend cycle.

-Jeff