From: David Laight <David.Laight@ACULAB.COM>
To: 'Manivannan Sadhasivam' <manivannan.sadhasivam@linaro.org>
Cc: "mhi@lists.linux.dev" <mhi@lists.linux.dev>,
"quic_hemantk@quicinc.com" <quic_hemantk@quicinc.com>,
"quic_bbhatt@quicinc.com" <quic_bbhatt@quicinc.com>,
"quic_jhugo@quicinc.com" <quic_jhugo@quicinc.com>,
"vinod.koul@linaro.org" <vinod.koul@linaro.org>,
"bjorn.andersson@linaro.org" <bjorn.andersson@linaro.org>,
"dmitry.baryshkov@linaro.org" <dmitry.baryshkov@linaro.org>,
"quic_vbadigan@quicinc.com" <quic_vbadigan@quicinc.com>,
"quic_cang@quicinc.com" <quic_cang@quicinc.com>,
"quic_skananth@quicinc.com" <quic_skananth@quicinc.com>,
"linux-arm-msm@vger.kernel.org" <linux-arm-msm@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"elder@linaro.org" <elder@linaro.org>
Subject: RE: [PATCH v4 05/27] bus: mhi: Use bitfield operations for handling DWORDs of ring elements
Date: Mon, 28 Feb 2022 15:40:56 +0000 [thread overview]
Message-ID: <8433702975794b5389563393bf7bc405@AcuMS.aculab.com> (raw)
In-Reply-To: <20220228144336.GB12451@workstation>
From: 'Manivannan Sadhasivam'
> Sent: 28 February 2022 14:44
>
> On Mon, Feb 28, 2022 at 02:00:07PM +0000, David Laight wrote:
> > From: Manivannan Sadhasivam
> > > Sent: 28 February 2022 12:43
> > >
> > > Instead of using the hardcoded bits in DWORD definitions, let's use the
> > > bitfield operations to make it more clear how the DWORDs are structured.
> >
> > That all makes it as clear as mud.
>
> It depends on how you see it ;)
>
> For instance,
>
> #define MHI_TRE_GET_CMD_TYPE(tre) ((MHI_TRE_GET_DWORD(tre, 1) >> 16) & 0xFF)
>
> vs
>
> #define MHI_TRE_GET_CMD_TYPE(tre) (FIELD_GET(GENMASK(23, 16), (MHI_TRE_GET_DWORD(tre, 1))))
>
> The later one makes it more obvious that the "type" field resides between bit 23
> and 16. Plus it avoids the extra masking.
No, (x >> 16) & 0xff is obviously bits 23 to 16.
I can guess or try to remember what FIELD_GET() and GENMASK() do
but it is really hard work.
Both lines are actually too long to read - especially given the
number of times they are repeated with very minor changes.
I actually wonder if you shouldn't just have a struct like:
struct mhi_cmd {
__le64 address;
__le16 len;
u8 state;
u8 vid;
__le16 xxx; /* I can't see what this is */
u8 chid;
u8 cmd;
};
although you might need the odd anonymous union/struct
to get the overlays in.
Even using something like:
#define MAKE_WORD0(len, state, vid) (htole16(len) | state << 16 | vid << 16)
would make for easier reading.
Oh yes, there are some 64bit fields here.
So a 'word' is 64 bits, so a 'double word' would be 128 bits!
WTF is a DWORD anyway????
Are you going to start using DWORD_PTR as well ?????
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2022-02-28 15:41 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-28 12:43 [PATCH v4 00/27] Add initial support for MHI endpoint stack Manivannan Sadhasivam
2022-02-28 12:43 ` [PATCH v4 01/27] bus: mhi: Fix pm_state conversion to string Manivannan Sadhasivam
2022-02-28 15:30 ` Alex Elder
2022-02-28 12:43 ` [PATCH v4 02/27] bus: mhi: Fix MHI DMA structure endianness Manivannan Sadhasivam
2022-02-28 15:40 ` Alex Elder
2022-02-28 12:43 ` [PATCH v4 03/27] bus: mhi: Move host MHI code to "host" directory Manivannan Sadhasivam
2022-02-28 12:43 ` [PATCH v4 04/27] bus: mhi: Use bitfield operations for register read and write Manivannan Sadhasivam
2022-02-28 12:43 ` [PATCH v4 05/27] bus: mhi: Use bitfield operations for handling DWORDs of ring elements Manivannan Sadhasivam
2022-02-28 14:00 ` David Laight
2022-02-28 14:43 ` 'Manivannan Sadhasivam'
2022-02-28 15:11 ` Alex Elder
2022-02-28 15:40 ` David Laight [this message]
2022-02-28 15:51 ` Alex Elder
2022-02-28 12:43 ` [PATCH v4 06/27] bus: mhi: Cleanup the register definitions used in headers Manivannan Sadhasivam
2022-02-28 12:43 ` [PATCH v4 07/27] bus: mhi: host: Rename "struct mhi_tre" to "struct mhi_ring_element" Manivannan Sadhasivam
2022-02-28 15:52 ` Alex Elder
2022-02-28 12:43 ` [PATCH v4 08/27] bus: mhi: Move common MHI definitions out of host directory Manivannan Sadhasivam
2022-02-28 12:43 ` [PATCH v4 09/27] bus: mhi: Make mhi_state_str[] array static inline and move to common.h Manivannan Sadhasivam
2022-02-28 15:56 ` Alex Elder
2022-02-28 12:43 ` [PATCH v4 10/27] bus: mhi: ep: Add support for registering MHI endpoint controllers Manivannan Sadhasivam
2022-02-28 16:06 ` Alex Elder
2022-02-28 12:43 ` [PATCH v4 11/27] bus: mhi: ep: Add support for registering MHI endpoint client drivers Manivannan Sadhasivam
2022-02-28 16:09 ` Alex Elder
2022-02-28 12:43 ` [PATCH v4 12/27] bus: mhi: ep: Add support for creating and destroying MHI EP devices Manivannan Sadhasivam
2022-02-28 16:10 ` Alex Elder
2022-02-28 12:43 ` [PATCH v4 13/27] bus: mhi: ep: Add support for managing MMIO registers Manivannan Sadhasivam
2022-02-28 16:23 ` Alex Elder
2022-02-28 12:43 ` [PATCH v4 14/27] bus: mhi: ep: Add support for ring management Manivannan Sadhasivam
2022-02-28 16:27 ` Alex Elder
2022-02-28 12:43 ` [PATCH v4 15/27] bus: mhi: ep: Add support for sending events to the host Manivannan Sadhasivam
2022-02-28 16:37 ` Alex Elder
2022-02-28 12:43 ` [PATCH v4 16/27] bus: mhi: ep: Add support for managing MHI state machine Manivannan Sadhasivam
2022-02-28 16:41 ` Alex Elder
2022-02-28 12:43 ` [PATCH v4 17/27] bus: mhi: ep: Add support for processing MHI endpoint interrupts Manivannan Sadhasivam
2022-02-28 16:45 ` Alex Elder
2022-03-01 6:41 ` Manivannan Sadhasivam
2022-02-28 12:43 ` [PATCH v4 18/27] bus: mhi: ep: Add support for powering up the MHI endpoint stack Manivannan Sadhasivam
2022-02-28 16:47 ` Alex Elder
2022-02-28 12:43 ` [PATCH v4 19/27] bus: mhi: ep: Add support for powering down " Manivannan Sadhasivam
2022-02-28 16:49 ` Alex Elder
2022-02-28 12:43 ` [PATCH v4 20/27] bus: mhi: ep: Add support for handling MHI_RESET Manivannan Sadhasivam
2022-02-28 12:43 ` [PATCH v4 21/27] bus: mhi: ep: Add support for handling SYS_ERR condition Manivannan Sadhasivam
2022-02-28 12:43 ` [PATCH v4 22/27] bus: mhi: ep: Add support for processing command rings Manivannan Sadhasivam
2022-02-28 12:43 ` [PATCH v4 23/27] bus: mhi: ep: Add support for reading from the host Manivannan Sadhasivam
2022-02-28 12:43 ` [PATCH v4 24/27] bus: mhi: ep: Add support for processing channel rings Manivannan Sadhasivam
2022-02-28 12:43 ` [PATCH v4 25/27] bus: mhi: ep: Add support for queueing SKBs to the host Manivannan Sadhasivam
2022-02-28 16:51 ` Alex Elder
2022-02-28 12:43 ` [PATCH v4 26/27] bus: mhi: ep: Add support for suspending and resuming channels Manivannan Sadhasivam
2022-02-28 12:43 ` [PATCH v4 27/27] bus: mhi: ep: Add uevent support for module autoloading Manivannan Sadhasivam
2022-02-28 16:57 ` [PATCH v4 00/27] Add initial support for MHI endpoint stack Alex Elder
2022-03-01 6:15 ` Manivannan Sadhasivam
2022-03-01 8:50 ` Manivannan Sadhasivam
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