AMD is losing discrete notebook market share because the first iteration of GCN wasn't optimized for notebook (something they are currently changing).
GCN works very well with notebooks, the problem isn't a hardware problem, its a management problem.
(Yes the following is to do a lot with GPUs but its mainly to illustrate the poor execution AMD has done on the mobile side).
The problem isn't that AMD can't field notebook parts its that it appears that AMD has no interest in discrete GPU in notebooks. AMD is focused on their APUs much to the detriment their discrete GPU division in notebooks (unfortunatly while APUs may be the future the margin on a single chip is probably less than they would get from CPU + GPU).
Main Problems with AMD in notebook
1. Drivers are extremely bad compared to nvidia. Enduro doesn't work as well as optimus (though greatly improved). For a year after launch the 7970m had driver problems with enduro. AMD denied the issue and attempted to block forum posters. This is a minor problem and should have been fixed pronto.
Drivers on mobile are extremely finicky and to update catalyst drivers you need the OEM driver release (which most OEMs don't do). Nvidia has this problem too but its not nearly as bad.
Loss of driver support for anything sub Evergreen (HD 4000 and below don't get updates).
Again this is a problem in management.
2. Broken Hybrid Crossfire (and regular crossfire for that matter).
3. Management failure to implement 45 watt CPUs for mobile (which would greatly improve performance in larger notebooks and a lot of the lower end notebooks are 15.6" and can take the heat easily). No brainer when competing with 45 watt intel CPUs.
4. Lack of mobile models. HD 7750/7770 are perfect for mobile but there are very few GCN chips in the 7xxx series that are actually common (only the 7730m and 7970m are popular). This isn't that they don't have the chips its that they simply aren't making the chips available to mobile. A 7790 based mobile chip would be really nice for mobile yet is nowhere to be found. AMD has instead released the 384 shader 87xxm series which generally falls in with nvidia's 730m (behind the curve). 88xx chips aren't found and there is a huge jump between the 640 shader 8870m and the 1280 shader 8970m (nvidia has this nicely filled in). They simply are not releasing the hardware.
5. Rebranding. AMD on the mobile side has been an absolute mess. 7730m performs better than the 8730m; the 6750m/6770m was a winning chip in mobile being significantly stronger than nvidia's mainstream chip the 540m at a similar price but what does AMD do for the 7xxx series rebrand? Drop clocks and GDDR5 support.
3D 11 mark gpu score (notebookcheck)
6770m - 1328
6750m - 1158
7670m - 1079
Thats right the Turks mobile refresh dropped the clock rate and GDDR5 support. The predecessor of the exact same chip performed significantly better than its successor (though the 7670m is found in much cheaper notebooks).
6xxx series was quite competitive vs nvidia but vs the 7xxx series nvidia performs much better (and is available) and nvidia's 7xxm series just walks away. (730m, nvidia's low end model just walk away from AMD's mid range, 1777 points vs 1534 for the 8750m).
Again AMD's management needs to get the chips on the table. There is literally no point to releasing a 384 core mainstream chip that's WEAKER than pretty much your competitor's weakest chip that isn't the barest entry level. POOR BUSINESS DECISIONS. They instead should have worked on a 7790 based chip. (And yes they spent the R&D to design this chip which pretty much is only found in mobile (also a few OEM desktop chips) probably only so they could try to hybrid crossfire with trinity/richland with their broken hybrid crossfire when they should have been working simply on the drivers for hybrid crossfire with Kaveri (and crossfire in general).
Other problems
1. The release of Bulldozer (obvious failure and should have cut their losses and just moved an impoved phenom 2 to 32 nm-- die shrunk phenom II would probably be more efficient than piledriver given some newer powersaving features).
2. Need to work with OEMs to produce convincing products. Kabini thin and lights for example.
So you can easily see that AMD is a complete mess mainly because of management. Hardware (GPU, Kabini/Temash are nice improvements) is very good but support is generally poor.