Re: [PATCH RFC 0/2] Eliminate drive_get_next()
Peter Maydell writes: > On Mon, 15 Nov 2021 at 12:55, Markus Armbruster wrote: >> >> This is RFC because I'm unsure about the removal of >> >> /* Reason: init() method uses drive_get_next() */ >> dc->user_creatable = false; >> >> in PATCH 1. Both users appear to wire up some GPIO. If that's >> necessary for the thing to work, we should just replace the comment. > > Looking at the code, it sort of is and sort of isn't. The GPIO line > is the chip-select line. If you don't connect it then (because the > ssi-sd device configures cs_polarity to SSI_CS_LOW, requesting an > active-low chip-select) the device will always be selected. If > the machine created an SSI bus with no SSI device attached to it > then in theory the user could create an ssi-sd device and connect > it there and have it work. But in practice it's really unlikely: > machines create SSI buses with specific wired-in devices on them, > and the guest OS knows what it has to do to enable the chip select > for the device it wants to talk to (often some known GPIO pin on > a GPIO controller). > > So I would keep the user_creatable = false, with a reason of > "user should wire up GPIO chip-select line". But see below for I'll do it this way. > a pile of contrary precedent. > > (The chip-select GPIO is created in the parent class, incidentally.) > >> Aside: there may be devices that need manual wiring to work, yet don't >> have user_creatable unset. Bugs if you ask me. I don't have smart >> ideas on how to track them down. > > Me neither. I notice that the TYPE_M25P80 is also an SSI peripheral > with an active-low chipselect but that one doesn't set user_creatable > to false. TYPE_SSD0323 also is user-creatable and that one has an > active-high chipselect, which means the user can create a device but > it will then never be usable because it will ignore all transactions. > (More generally, looks like most subclasses of TYPE_SSI_PERIPHERAL > don't set user_creatable = false.) For sysbus devices, we clear user_creatable by default, because sysbus devices pretty much always[*] need wiring. Is this the case for SSI bus devices, too? [*] The most prominent exception is "dynamic sysbus", which I believe was a mistake.
Re: [PATCH RFC 0/2] Eliminate drive_get_next()
On Mon, 15 Nov 2021 at 12:55, Markus Armbruster wrote: > > This is RFC because I'm unsure about the removal of > > /* Reason: init() method uses drive_get_next() */ > dc->user_creatable = false; > > in PATCH 1. Both users appear to wire up some GPIO. If that's > necessary for the thing to work, we should just replace the comment. Looking at the code, it sort of is and sort of isn't. The GPIO line is the chip-select line. If you don't connect it then (because the ssi-sd device configures cs_polarity to SSI_CS_LOW, requesting an active-low chip-select) the device will always be selected. If the machine created an SSI bus with no SSI device attached to it then in theory the user could create an ssi-sd device and connect it there and have it work. But in practice it's really unlikely: machines create SSI buses with specific wired-in devices on them, and the guest OS knows what it has to do to enable the chip select for the device it wants to talk to (often some known GPIO pin on a GPIO controller). So I would keep the user_creatable = false, with a reason of "user should wire up GPIO chip-select line". But see below for a pile of contrary precedent. (The chip-select GPIO is created in the parent class, incidentally.) > Aside: there may be devices that need manual wiring to work, yet don't > have user_creatable unset. Bugs if you ask me. I don't have smart > ideas on how to track them down. Me neither. I notice that the TYPE_M25P80 is also an SSI peripheral with an active-low chipselect but that one doesn't set user_creatable to false. TYPE_SSD0323 also is user-creatable and that one has an active-high chipselect, which means the user can create a device but it will then never be usable because it will ignore all transactions. (More generally, looks like most subclasses of TYPE_SSI_PERIPHERAL don't set user_creatable = false.) -- PMM
[PATCH RFC 0/2] Eliminate drive_get_next()
This is RFC because I'm unsure about the removal of /* Reason: init() method uses drive_get_next() */ dc->user_creatable = false; in PATCH 1. Both users appear to wire up some GPIO. If that's necessary for the thing to work, we should just replace the comment. Aside: there may be devices that need manual wiring to work, yet don't have user_creatable unset. Bugs if you ask me. I don't have smart ideas on how to track them down. Markus Armbruster (2): hw/sd/ssi-sd: Do not create SD card within controller's realize hw: Replace drive_get_next() by drive_get() include/sysemu/blockdev.h | 1 - blockdev.c | 10 -- hw/arm/aspeed.c | 21 + hw/arm/cubieboard.c | 2 +- hw/arm/imx25_pdk.c | 2 +- hw/arm/integratorcp.c | 2 +- hw/arm/mcimx6ul-evk.c | 2 +- hw/arm/mcimx7d-sabre.c | 2 +- hw/arm/msf2-som.c | 2 +- hw/arm/npcm7xx_boards.c | 6 +++--- hw/arm/orangepi.c | 2 +- hw/arm/raspi.c | 2 +- hw/arm/realview.c | 2 +- hw/arm/sabrelite.c | 2 +- hw/arm/stellaris.c | 15 ++- hw/arm/versatilepb.c| 4 ++-- hw/arm/vexpress.c | 6 +++--- hw/arm/xilinx_zynq.c| 16 +--- hw/arm/xlnx-versal-virt.c | 3 ++- hw/arm/xlnx-zcu102.c| 6 +++--- hw/microblaze/petalogix_ml605_mmu.c | 2 +- hw/misc/sifive_u_otp.c | 2 +- hw/riscv/microchip_pfsoc.c | 2 +- hw/riscv/sifive_u.c | 15 +-- hw/sd/ssi-sd.c | 29 - hw/sparc64/niagara.c| 2 +- 26 files changed, 76 insertions(+), 84 deletions(-) -- 2.31.1
