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Message-ID: <2dba47561b467c483263b65606aa3e79c05c91a3.camel@linux.intel.com>
Subject: Re: [PATCH V2 2/9] platform/x86/intel/sdsi: Combine read and write
 mailbox flows
From: "David E. Box" <david.e.box@linux.intel.com>
Reply-To: david.e.box@linux.intel.com
To: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>,
  rajvi.jingar@linux.intel.com, platform-driver-x86@vger.kernel.org, 
 linux-kernel@vger.kernel.org, hdegoede@redhat.com,
 ilpo.jarvinen@linux.intel.com
Date: Wed, 28 Feb 2024 10:10:11 -0800
In-Reply-To: <dd9ab7d1-5c03-404a-90c7-7ccbc0fb5c4c@linux.intel.com>
References: <20240228000016.1685518-1-david.e.box@linux.intel.com>
	 <20240228000016.1685518-3-david.e.box@linux.intel.com>
	 <dd9ab7d1-5c03-404a-90c7-7ccbc0fb5c4c@linux.intel.com>
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Organization: David E. Box
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On Tue, 2024-02-27 at 18:38 -0800, Kuppuswamy Sathyanarayanan wrote:
>=20
> On 2/27/24 4:00 PM, David E. Box wrote:
> > The current mailbox commands are either read-only or write-only and the
> > flow is different for each. New commands will need to send and receive
> > data. In preparation for these commands, create a common polling functi=
on
> > to handle sending data and receiving in the same transaction.
> >=20
> > Signed-off-by: David E. Box <david.e.box@linux.intel.com>
> > ---
> >=20
> > V2 - In sdsi_cmd_read() remove unnecessary check for non-zero packet_si=
ze
> > =C2=A0=C2=A0=C2=A0=C2=A0 in do loop since the loop is exited earlier wh=
en packet_size is
> > =C2=A0=C2=A0=C2=A0=C2=A0 zero.
> >=20
> > =C2=A0drivers/platform/x86/intel/sdsi.c | 79 +++++++++++++++++---------=
-----
> > =C2=A01 file changed, 44 insertions(+), 35 deletions(-)
> >=20
> > diff --git a/drivers/platform/x86/intel/sdsi.c
> > b/drivers/platform/x86/intel/sdsi.c
> > index a70c071de6e2..d80c2dc0ce71 100644
> > --- a/drivers/platform/x86/intel/sdsi.c
> > +++ b/drivers/platform/x86/intel/sdsi.c
> > @@ -15,6 +15,7 @@
> > =C2=A0#include <linux/iopoll.h>
> > =C2=A0#include <linux/kernel.h>
> > =C2=A0#include <linux/module.h>
> > +#include <linux/overflow.h>
> > =C2=A0#include <linux/pci.h>
> > =C2=A0#include <linux/slab.h>
> > =C2=A0#include <linux/sysfs.h>
> > @@ -156,8 +157,8 @@ static int sdsi_status_to_errno(u32 status)
> > =C2=A0	}
> > =C2=A0}
> > =C2=A0
> > -static int sdsi_mbox_cmd_read(struct sdsi_priv *priv, struct sdsi_mbox=
_info
> > *info,
> > -			=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 size_t *data_size)
> > +static int sdsi_mbox_poll(struct sdsi_priv *priv, struct sdsi_mbox_inf=
o
> > *info,
> > +			=C2=A0 size_t *data_size)
> > =C2=A0{
> > =C2=A0	struct device *dev =3D priv->dev;
> > =C2=A0	u32 total, loop, eom, status, message_size;
> > @@ -166,18 +167,10 @@ static int sdsi_mbox_cmd_read(struct sdsi_priv *p=
riv,
> > struct sdsi_mbox_info *inf
> > =C2=A0
> > =C2=A0	lockdep_assert_held(&priv->mb_lock);
> > =C2=A0
> > -	/* Format and send the read command */
> > -	control =3D FIELD_PREP(CTRL_EOM, 1) |
> > -		=C2=A0 FIELD_PREP(CTRL_SOM, 1) |
> > -		=C2=A0 FIELD_PREP(CTRL_RUN_BUSY, 1) |
> > -		=C2=A0 FIELD_PREP(CTRL_PACKET_SIZE, info->size);
> > -	writeq(control, priv->control_addr);
> > -
> > =C2=A0	/* For reads, data sizes that are larger than the mailbox size a=
re
> > read in packets. */
> > =C2=A0	total =3D 0;
> > =C2=A0	loop =3D 0;
> > =C2=A0	do {
> > -		void *buf =3D info->buffer + (SDSI_SIZE_MAILBOX * loop);
> > =C2=A0		u32 packet_size;
> > =C2=A0
> > =C2=A0		/* Poll on ready bit */
> > @@ -195,6 +188,11 @@ static int sdsi_mbox_cmd_read(struct sdsi_priv *pr=
iv,
> > struct sdsi_mbox_info *inf
> > =C2=A0		if (ret)
> > =C2=A0			break;
> > =C2=A0
> > +		if (!packet_size) {
> > +			sdsi_complete_transaction(priv);
> > +			break;
> > +		}
> > +
> > =C2=A0		/* Only the last packet can be less than the mailbox size.
> > */
> > =C2=A0		if (!eom && packet_size !=3D SDSI_SIZE_MAILBOX) {
> > =C2=A0			dev_err(dev, "Invalid packet size\n");
> > @@ -208,9 +206,13 @@ static int sdsi_mbox_cmd_read(struct sdsi_priv *pr=
iv,
> > struct sdsi_mbox_info *inf
> > =C2=A0			break;
> > =C2=A0		}
> > =C2=A0
> > -		sdsi_memcpy64_fromio(buf, priv->mbox_addr,
> > round_up(packet_size, SDSI_SIZE_CMD));
> > +		if (info->buffer) {
> > +			void *buf =3D info->buffer +
> > array_size(SDSI_SIZE_MAILBOX, loop);
> > =C2=A0
> > -		total +=3D packet_size;
> > +			sdsi_memcpy64_fromio(buf, priv->mbox_addr,
> > +					=C2=A0=C2=A0=C2=A0=C2=A0 round_up(packet_size,
> > SDSI_SIZE_CMD));
> > +			total +=3D packet_size;
> > +		}
> > =C2=A0
> > =C2=A0		sdsi_complete_transaction(priv);
> > =C2=A0	} while (!eom && ++loop < MBOX_MAX_PACKETS);
> > @@ -230,16 +232,33 @@ static int sdsi_mbox_cmd_read(struct sdsi_priv *p=
riv,
> > struct sdsi_mbox_info *inf
> > =C2=A0		dev_warn(dev, "Read count %u differs from expected count
> > %u\n",
> > =C2=A0			 total, message_size);
> > =C2=A0
> > -	*data_size =3D total;
> > +	if (data_size)
> > +		*data_size =3D total;
> > =C2=A0
>=20
> Is there a chance for it to be NULL with current callers?

Yes. Write only callers set this to NULL.

David