diff mbox

[v4] libata-scsi: better style in ata_msense_*()

Message ID 578e9008.4500420a.2d828.d131@mx.google.com
State Not Applicable
Delegated to: David Miller
Headers show

Commit Message

Tom Yan July 19, 2016, 8:39 p.m. UTC 
From: Tom Yan <tom.ty89@gmail.com>

`changeable` is the "version" of mode page requested by the user.
It will be less confusing/misleading if we do not check it
"together" with the setting bits of the drive.

Not to mention that we currently have ata_mselect_*() implemented
in a way that each of them will serve exclusively a particular bit
on each page. The old style will hence make the condition look even
more unnecessarily arcane if the ata_msense_*() is reflecting more
than one bit.

Signed-off-by: Tom Yan <tom.ty89@gmail.com>

Comments

Tom Yan July 19, 2016, 8:44 p.m. UTC | #1 
FWIW, I end up using `bool d_sense = (dev->flags &
ATA_DFLAG_D_SENSE)`, which was introduced to ata_scsi_set_sense() in
commit 06dbde5f3a44 ("libata: Implement control mode page to select
sense format"), in the polished ata_msense_control().

@Sergei, I kept the parentheses for the bit shifting/masking results
because it appears that the rest of the code in libata-scsi.c does
that as well. So I am not going to partially clean up that to avoid
making it look inconsistent.

On 20 July 2016 at 04:39,  <tom.ty89@gmail.com> wrote:
> From: Tom Yan <tom.ty89@gmail.com>
>
> `changeable` is the "version" of mode page requested by the user.
> It will be less confusing/misleading if we do not check it
> "together" with the setting bits of the drive.
>
> Not to mention that we currently have ata_mselect_*() implemented
> in a way that each of them will serve exclusively a particular bit
> on each page. The old style will hence make the condition look even
> more unnecessarily arcane if the ata_msense_*() is reflecting more
> than one bit.
>
> Signed-off-by: Tom Yan <tom.ty89@gmail.com>
>
> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
> index bf4cb21..b00521b 100644
> --- a/drivers/ata/libata-scsi.c
> +++ b/drivers/ata/libata-scsi.c
> @@ -2424,10 +2424,12 @@ static void modecpy(u8 *dest, const u8 *src, int n, bool changeable)
>  static unsigned int ata_msense_caching(u16 *id, u8 *buf, bool changeable)
>  {
>         modecpy(buf, def_cache_mpage, sizeof(def_cache_mpage), changeable);
> -       if (changeable || ata_id_wcache_enabled(id))
> -               buf[2] |= (1 << 2);     /* write cache enable */
> -       if (!changeable && !ata_id_rahead_enabled(id))
> -               buf[12] |= (1 << 5);    /* disable read ahead */
> +       if (changeable) {
> +               buf[2] |= (1 << 2);     /* ata_mselect_caching() */
> +       } else {
> +               buf[2] |= (ata_id_wcache_enabled(id) << 2);     /* write cache enable */
> +               buf[12] |= (!ata_id_rahead_enabled(id) << 5);   /* disable read ahead */
> +       }
>         return sizeof(def_cache_mpage);
>  }
>
> @@ -2446,8 +2448,13 @@ static unsigned int ata_msense_control(struct ata_device *dev, u8 *buf,
>                                         bool changeable)
>  {
>         modecpy(buf, def_control_mpage, sizeof(def_control_mpage), changeable);
> -       if (changeable || (dev->flags & ATA_DFLAG_D_SENSE))
> -               buf[2] |= (1 << 2);     /* Descriptor sense requested */
> +       if (changeable) {
> +               buf[2] |= (1 << 2);     /* ata_mselect_control() */
> +       } else {
> +               bool d_sense = (dev->flags & ATA_DFLAG_D_SENSE);
> +
> +               buf[2] |= (d_sense << 2);       /* descriptor format sense data */
> +       }
>         return sizeof(def_control_mpage);
>  }
>
> --
> 2.9.0
>
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Tejun Heo July 20, 2016, 3:22 p.m. UTC | #2 
On Wed, Jul 20, 2016 at 04:39:28AM +0800, tom.ty89@gmail.com wrote:
> From: Tom Yan <tom.ty89@gmail.com>
> 
> `changeable` is the "version" of mode page requested by the user.
> It will be less confusing/misleading if we do not check it
> "together" with the setting bits of the drive.
> 
> Not to mention that we currently have ata_mselect_*() implemented
> in a way that each of them will serve exclusively a particular bit
> on each page. The old style will hence make the condition look even
> more unnecessarily arcane if the ata_msense_*() is reflecting more
> than one bit.
> 
> Signed-off-by: Tom Yan <tom.ty89@gmail.com>

Applied to libata/for-4.8.

Thanks.
diff mbox

Patch

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index bf4cb21..b00521b 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -2424,10 +2424,12 @@  static void modecpy(u8 *dest, const u8 *src, int n, bool changeable)
 static unsigned int ata_msense_caching(u16 *id, u8 *buf, bool changeable)
 {
 	modecpy(buf, def_cache_mpage, sizeof(def_cache_mpage), changeable);
-	if (changeable || ata_id_wcache_enabled(id))
-		buf[2] |= (1 << 2);	/* write cache enable */
-	if (!changeable && !ata_id_rahead_enabled(id))
-		buf[12] |= (1 << 5);	/* disable read ahead */
+	if (changeable) {
+		buf[2] |= (1 << 2);	/* ata_mselect_caching() */
+	} else {
+		buf[2] |= (ata_id_wcache_enabled(id) << 2);	/* write cache enable */
+		buf[12] |= (!ata_id_rahead_enabled(id) << 5);	/* disable read ahead */
+	}
 	return sizeof(def_cache_mpage);
 }
 
@@ -2446,8 +2448,13 @@  static unsigned int ata_msense_control(struct ata_device *dev, u8 *buf,
 					bool changeable)
 {
 	modecpy(buf, def_control_mpage, sizeof(def_control_mpage), changeable);
-	if (changeable || (dev->flags & ATA_DFLAG_D_SENSE))
-		buf[2] |= (1 << 2);	/* Descriptor sense requested */
+	if (changeable) {
+		buf[2] |= (1 << 2);	/* ata_mselect_control() */
+	} else {
+		bool d_sense = (dev->flags & ATA_DFLAG_D_SENSE);
+
+		buf[2] |= (d_sense << 2);	/* descriptor format sense data */
+	}
 	return sizeof(def_control_mpage);
 }