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From: Todd Poynor <toddpoynor@gmail.com>
To: Rob Springer <rspringer@google.com>,
	Ben Chan <benchan@chromium.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org,
	Nick Ewalt <nicholasewalt@google.com>,
	Todd Poynor <toddpoynor@google.com>
Subject: [PATCH 11/11] staging: gasket: Update device virtual address comment
Date: Sun, 14 Oct 2018 21:59:27 -0700	[thread overview]
Message-ID: <20181015045927.156790-12-toddpoynor@gmail.com> (raw)
In-Reply-To: <20181015045927.156790-1-toddpoynor@gmail.com>

From: Nick Ewalt <nicholasewalt@google.com>

Add that number of page table entries and extended address bit offset
are configurable. Update example virtual address format to be more
consistent with typical usage.

Signed-off-by: Nick Ewalt <nicholasewalt@google.com>
Signed-off-by: Todd Poynor <toddpoynor@google.com>
---
 drivers/staging/gasket/gasket_page_table.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/gasket/gasket_page_table.c b/drivers/staging/gasket/gasket_page_table.c
index c2fbab74194f8..5b398b7ba81d3 100644
--- a/drivers/staging/gasket/gasket_page_table.c
+++ b/drivers/staging/gasket/gasket_page_table.c
@@ -10,10 +10,18 @@
  *
  * This file assumes 4kB pages throughout; can be factored out when necessary.
  *
- * Address format is as follows:
+ * There is a configurable number of page table entries, as well as a
+ * configurable bit index for the extended address flag. Both of these are
+ * specified in gasket_page_table_init through the page_table_config parameter.
+ *
+ * The following example assumes:
+ *   page_table_config->total_entries = 8192
+ *   page_table_config->extended_bit = 63
+ *
+ * Address format:
  * Simple addresses - those whose containing pages are directly placed in the
  * device's address translation registers - are laid out as:
- * [ 63 - 40: Unused | 39 - 28: 0 | 27 - 12: page index | 11 - 0: page offset ]
+ * [ 63 - 25: 0 | 24 - 12: page index | 11 - 0: page offset ]
  * page index:  The index of the containing page in the device's address
  *              translation registers.
  * page offset: The index of the address into the containing page.
@@ -21,7 +29,7 @@
  * Extended address - those whose containing pages are contained in a second-
  * level page table whose address is present in the device's address translation
  * registers - are laid out as:
- * [ 63 - 40: Unused | 39: flag | 38 - 37: 0 | 36 - 21: dev/level 0 index |
+ * [ 63: flag | 62 - 34: 0 | 33 - 21: dev/level 0 index |
  *   20 - 12: host/level 1 index | 11 - 0: page offset ]
  * flag:        Marker indicating that this is an extended address. Always 1.
  * dev index:   The index of the first-level page in the device's extended
-- 
2.19.0.605.g01d371f741-goog


  parent reply	other threads:[~2018-10-15  5:00 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-15  4:59 [PATCH 00/11] staging: gasket: fixes Todd Poynor
2018-10-15  4:59 ` [PATCH 01/11] staging: gasket: core: debug log updates Todd Poynor
2018-10-15  7:34   ` Greg Kroah-Hartman
2018-10-15 20:33     ` Todd Poynor
2018-10-15  4:59 ` [PATCH 02/11] staging: gasket: page table: return valid error code on map fail Todd Poynor
2018-10-15  4:59 ` [PATCH 03/11] staging: gasket: page table: remove dead code in coherent mem alloc Todd Poynor
2018-10-15  4:59 ` [PATCH 04/11] staging: gasket: page_table: remove unnecessary PTE status set to free Todd Poynor
2018-10-15  4:59 ` [PATCH 05/11] staging: gasket: page_table: rearrange gasket_page_table_entry Todd Poynor
2018-10-15  7:37   ` Greg Kroah-Hartman
2018-10-15  4:59 ` [PATCH 06/11] staging: gasket: page table: fixup error path allocating coherent mem Todd Poynor
2018-10-15  4:59 ` [PATCH 07/11] staging: gasket: page_table: fix comment in components_to_dev_address Todd Poynor
2018-10-15  4:59 ` [PATCH 08/11] staging: gasket: page_table: simplify gasket_components_to_dev_address Todd Poynor
2018-10-15  4:59 ` [PATCH 09/11] staging: gasket: apex: fix sysfs_show Todd Poynor
2018-10-15  4:59 ` [PATCH 10/11] staging: gasket: sysfs: fix attribute release comment Todd Poynor
2018-10-15  4:59 ` Todd Poynor [this message]
2018-10-15  7:33 ` [PATCH 00/11] staging: gasket: fixes Greg Kroah-Hartman
2018-10-15 10:19   ` Todd Poynor
2018-10-15 10:29 ` Christoph Hellwig
2018-10-15 10:35   ` Greg Kroah-Hartman

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