> Does DSP use virtual-to-physical mapping for all the > addresses it accesses (including DSP's local buffers)? > Or it uses this mapping only to access shared buffers? > Wont it be a big overhead if DSP accesses all the memories > through virtual-to-physical mapping?
DSP has to access all the external memory buffers through DSP MMU. Best Regards Vijay > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Viraj > Karandikar > Sent: Monday, June 09, 2008 10:18 AM > To: Gupta, Ramesh; linux-omap@vger.kernel.org > Subject: RE: Sharing buffers between ARM-DSP on OMAP3430 over Bridge > Viraj, > Thanks Ramesh. > I was reserving and mapping buffers "every time". This was > not required. > I modified the code to reserve and map a buffer only once and > use the mapped address for future. > This modification reduced the overhead. > > I have one more doubt. > Does DSP use virtual-to-physical mapping for all the > addresses it accesses (including DSP's local buffers)? > Or it uses this mapping only to access shared buffers? > Wont it be a big overhead if DSP accesses all the memories > through virtual-to-physical mapping? > > Regards, > Viraj > > > > -----Original Message----- > From: Ramesh Gupta G [mailto:[EMAIL PROTECTED] > Sent: Monday, June 09, 2008 11:03 AM > To: Viraj Karandikar; [EMAIL PROTECTED] > Subject: Re: Sharing buffers between ARM-DSP on OMAP3430 over Bridge > > Hi Vijay, > > ----- Original Message ----- > From: "Viraj Karandikar" <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Sent: Saturday, June 07, 2008 3:45 PM > Subject: Sharing buffers between ARM-DSP on OMAP3430 over Bridge > > > >Hi all, > > >I am working on omap3430 using bridge. I am using Dynamically Mapped > >Memory (DMM) method for sharing buffers. > > >For sending buffers to DSP I am doing calls to > >DSPProcessor_ReserveMemory() and DSPProcessor_Map(). For these calls > are > >taking around 18ms (for 3-4MB buffers) which is not > acceptable for the > >application. I am not able to understand why it is taking so > much time? > > Which version of bridge you are using? > We have optimized the code for DSPProcessor_Map(), You can see > significant > change in the > numbers with the latest code. > > > >My understanding of DMM method is -> > > > >- Use malloc() to allocate a buffer on ARM. > > >- Reserve required chunk of memory from DMM pool (using > >DSPProcessor_ReserveMemory() ) > > >- Translate this memory to ARM virtual address space in > >DSPProcessor_Map() function. > > Actually DSPProcessor_Map() maps ARM physical addresses to DSP Virtual > addresses. > > >- Send the reserved memory address to DSP. > > > > >Is this correct? I am confused about how exactly this happens. > > You are correct except above point about DSPProcessor_Map(). > > >Also Ihave a doubt if the reserved memory address is from > DSP physical > address > >space? Or is it from ARM virtual address space for DSP > physical address > >space? > > Reserved Memory is from DSP Virtual Address. > > >Is DMM method does copy from malloc'ed address to reserved > >address in any way? > > Do you mean copying the contents? No copying is involved. Only mapping > of > addresses is performed. > > > >It will be helpful if anybody put some light on this. > > Please let me know if you see any issues. > > > > >Regards, > > >Viraj > > > Thanks & Regards > Ramesh Gupta G > > ********************************************************************** > This email and any files transmitted with it are confidential and > intended solely for the use of the individual or entity to whom they > are addressed. If you have received this email in error please notify > [EMAIL PROTECTED] > ********************************************************************** > > _______________________________________________ > Linux-omap-open-source mailing list > [EMAIL PROTECTED] > http://linux.omap.com/mailman/listinfo/linux-omap-open-source > > -- > To unsubscribe from this list: send the line "unsubscribe > linux-omap" in > the body of a message to [EMAIL PROTECTED] > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
