From 4963ac3632dda7433db5149d6abdfc644a8d8ab2 Mon Sep 17 00:00:00 2001 From: Sukadev Bhattiprolu Date: Tue, 7 Nov 2017 18:23:44 -0800 Subject: [PATCH] powerpc/vas: Drop poll_window_cast_out(). Polling for window cast out is listed in the spec, but turns out that it is not strictly necessary and slows down window close. Making it a stub for now. Signed-off-by: Sukadev Bhattiprolu Signed-off-by: Michael Ellerman --- arch/powerpc/platforms/powernv/vas-window.c | 34 ++++++++++----------- 1 file changed, 17 insertions(+), 17 deletions(-) diff --git a/arch/powerpc/platforms/powernv/vas-window.c b/arch/powerpc/platforms/powernv/vas-window.c index 67ffc5d994cc..8ab8a8208347 100644 --- a/arch/powerpc/platforms/powernv/vas-window.c +++ b/arch/powerpc/platforms/powernv/vas-window.c @@ -1079,25 +1079,25 @@ static void poll_window_busy_state(struct vas_window *window) } } +/* + * Have the hardware cast a window out of cache and wait for it to + * be completed. + * + * NOTE: It can take a relatively long time to cast the window context + * out of the cache. It is not strictly necessary to cast out if: + * + * - we clear the "Pin Window" bit (so hardware is free to evict) + * + * - we re-initialize the window context when it is reassigned. + * + * We do the former in vas_win_close() and latter in vas_win_open(). + * So, ignoring the cast-out for now. We can add it as needed. If + * casting out becomes necessary we should consider offloading the + * job to a worker thread, so the window close can proceed quickly. + */ static void poll_window_castout(struct vas_window *window) { - int cached; - u64 val; - - /* Cast window context out of the cache */ -retry: - val = read_hvwc_reg(window, VREG(WIN_CTX_CACHING_CTL)); - cached = GET_FIELD(VAS_WIN_CACHE_STATUS, val); - if (cached) { - val = 0ULL; - val = SET_FIELD(VAS_CASTOUT_REQ, val, 1); - val = SET_FIELD(VAS_PUSH_TO_MEM, val, 0); - write_hvwc_reg(window, VREG(WIN_CTX_CACHING_CTL), val); - - set_current_state(TASK_UNINTERRUPTIBLE); - schedule_timeout(HZ); - goto retry; - } + /* stub for now */ } /* -- GitLab