linux-kernel - [PATCH 08/11] staging: gasket: page_table: simplify gasket_components_to_dev

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Date:   Sun, 14 Oct 2018 21:59:24 -0700
From:   Todd Poynor <toddpoynor@...il.com>
To:     Rob Springer <rspringer@...gle.com>,
        Ben Chan <benchan@...omium.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        Nick Ewalt <nicholasewalt@...gle.com>,
        Todd Poynor <toddpoynor@...gle.com>
Subject: [PATCH 08/11] staging: gasket: page_table: simplify gasket_components_to_dev_address

From: Nick Ewalt <nicholasewalt@...gle.com>

Refactor gasket_components_to_dev_address to be faster and easier to
understand. The old implementation was unnecessarily complex and masked
the page_index for simple addresses but not extended ones. It makes the
most sense for this function to perform no such masking.

Signed-off-by: Nick Ewalt <nicholasewalt@...gle.com>
Signed-off-by: Todd Poynor <toddpoynor@...gle.com>
---
 drivers/staging/gasket/gasket_page_table.c | 21 ++-------------------
 1 file changed, 2 insertions(+), 19 deletions(-)

diff --git a/drivers/staging/gasket/gasket_page_table.c b/drivers/staging/gasket/gasket_page_table.c
index ec9359576ea7c..c2fbab74194f8 100644
--- a/drivers/staging/gasket/gasket_page_table.c
+++ b/drivers/staging/gasket/gasket_page_table.c
@@ -699,26 +699,9 @@ static ulong gasket_components_to_dev_address(struct gasket_page_table *pg_tbl,
 					      int is_simple, uint page_index,
 					      uint offset)
 {
-	ulong lvl0_index, lvl1_index;
+	ulong dev_addr = (page_index << GASKET_SIMPLE_PAGE_SHIFT) | offset;
 
-	if (is_simple) {
-		/* Return simple addresses directly. */
-		lvl0_index = page_index & (pg_tbl->config.total_entries - 1);
-		return (lvl0_index << GASKET_SIMPLE_PAGE_SHIFT) | offset;
-	}
-
-	/*
-	 * This could be compressed into fewer statements, but
-	 * A) the compiler should optimize it
-	 * B) this is not slow
-	 * C) this is an uncommon operation
-	 * D) this is actually readable this way.
-	 */
-	lvl0_index = page_index / GASKET_PAGES_PER_SUBTABLE;
-	lvl1_index = page_index & (GASKET_PAGES_PER_SUBTABLE - 1);
-	return (pg_tbl)->extended_flag |
-	       (lvl0_index << GASKET_EXTENDED_LVL0_SHIFT) |
-	       (lvl1_index << GASKET_EXTENDED_LVL1_SHIFT) | offset;
+	return is_simple ? dev_addr : (pg_tbl->extended_flag | dev_addr);
 }
 
 /*
-- 
2.19.0.605.g01d371f741-goog