Re: [PATCH 0/5] auxdisplay: linedisp: support attribute attachment to auxdisplay devices

[Andy Shevchenko <andriy.shevchenko@intel.com>]

On Sun, Aug 31, 2025 at 10:00:24PM -0400, Jean-François Lessard wrote:
> This series modernizes the auxdisplay line display (linedisp) library to
> enable seamless integration with auxdisplay parent devices while
> maintaining backward compatibility.
> 
> The key improvement is adding attach/detach APIs that allow linedisp sysfs
> attributes to be bound directly to their parent auxdisplay devices avoiding
> child device proliferation and enabling a uniform 7-segment userspace
> interface across different driver architectures.
> 
> This series introduces attachment infrastructure for linedisp devices.
> The first consumer of this API will be the TM16XX driver series.
> See the related patch series:
>   auxdisplay: Add TM16xx 7-segment LED matrix display controllers driver
> 
> Changes include:
> 1. Encapsulate container_of() usage with to_linedisp() helper function for
>    cleaner context retrieval
> 2. Improve message display behavior with static padding when message length
>    is smaller than display width
> 3. Add 'num_chars' read-only attribute for userspace capability discovery
> 4. Add attach/detach API for sysfs attributes binding to parent devices
> 5. Document all linedisp sysfs attributes in ABI documentation
> 
> All existing linedisp_register() users remain unaffected. The new APIs
> enable drivers like TM16XX to integrate 7-segment functionality within
> their LED class device hierarchy while providing a uniform 7-segment API.
> 
> Thanks to Andy Shevchenko for early feedback and guidance.

Overall LGTM, only one question about spin lock vs. mutex. The rest is simple
nit-picks. I'll also wait for Geert's review / Acks.

-- 
With Best Regards,
Andy Shevchenko