Re: [PATCH v2] thunderbolt: Clamp DMA tunnel credits to what a hop register can hold

[Mika Westerberg]

Hi,

On Mon, Aug 10, 2026 at 12:14:13PM +0000, Fan Ye via B4 Relay wrote:
> From: Fan Ye <fy15309206903@xxxxxxxxx>
> 
> struct tb_regs_hop::initial_credits is 7 bits wide, but neither of the
> values tb_tunnel_alloc_dma() picks from is bounded by that: the
> dma_credits module parameter has no upper limit, and neither does the
> host router's baMaxHI. A larger count survives until tb_path_activate()
> copies it into the register and keeps the low bits, leaving the path on
> a credit count nobody asked for.
> 
> Clamp it in tb_tunnel_alloc_dma(), the only entry point for DMA tunnels;
> every step below it can only lower the value further. Carry the count in
> an unsigned int while at it.
> 
> Assisted-by: Claude:claude-opus-5
> Signed-off-by: Fan Ye <fy15309206903@xxxxxxxxx>

Applied to thunderbolt.git/next, thanks!